Improve code quality

57 files changed, 208 insertions, 180 deletions

diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/component/ComponentTreeBuilder.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/component/ComponentTreeBuilder.java
index 09c9f10ffa8..cc24fa8aa6b 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/component/ComponentTreeBuilder.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/component/ComponentTreeBuilder.java
@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.function.Function;
+import java.util.function.UnaryOperator;
 import javax.annotation.CheckForNull;
 import javax.annotation.Nullable;
 import org.apache.commons.io.FilenameUtils;
@@ -72,7 +73,7 @@ public class ComponentTreeBuilder {
   public ComponentTreeBuilder(
     ComponentKeyGenerator keyGenerator,
     ComponentKeyGenerator publicKeyGenerator,
-    Function<String, String> uuidSupplier,
+    UnaryOperator<String> uuidSupplier,
     Function<Integer, ScannerReport.Component> scannerComponentSupplier,
     Project project,
     Branch branch,
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/duplication/DuplicationMeasures.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/duplication/DuplicationMeasures.java
index e5224b836fc..28d030a2fa5 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/duplication/DuplicationMeasures.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/duplication/DuplicationMeasures.java
@@ -47,7 +47,7 @@ import static org.sonar.api.measures.CoreMetrics.DUPLICATED_LINES_KEY;
 import static org.sonar.api.measures.CoreMetrics.LINES_KEY;
 
 public class DuplicationMeasures {
-  protected final List<Formula> formulas;
+  protected final List<Formula<?>> formulas;
   protected final TreeRootHolder treeRootHolder;
   protected final MetricRepository metricRepository;
   protected final MeasureRepository measureRepository;
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/formula/FormulaExecutorComponentVisitor.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/formula/FormulaExecutorComponentVisitor.java
index 9d0cae21dd7..9871043b204 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/formula/FormulaExecutorComponentVisitor.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/formula/FormulaExecutorComponentVisitor.java
@@ -59,9 +59,9 @@ public class FormulaExecutorComponentVisitor extends PathAwareVisitorAdapter<For
 
   private final MetricRepository metricRepository;
   private final MeasureRepository measureRepository;
-  private final List<Formula> formulas;
+  private final List<Formula<?>> formulas;
 
-  private FormulaExecutorComponentVisitor(Builder builder, Iterable<Formula> formulas) {
+  private FormulaExecutorComponentVisitor(Builder builder, Iterable<Formula<?>> formulas) {
     super(CrawlerDepthLimit.LEAVES, ComponentVisitor.Order.POST_ORDER, COUNTERS_FACTORY);
     this.measureRepository = builder.measureRepository;
     this.metricRepository = builder.metricRepository;
@@ -85,7 +85,7 @@ public class FormulaExecutorComponentVisitor extends PathAwareVisitorAdapter<For
       return new Builder(metricRepository, measureRepository);
     }
 
-    public FormulaExecutorComponentVisitor buildFor(Iterable<Formula> formulas) {
+    public FormulaExecutorComponentVisitor buildFor(Iterable<Formula<?>> formulas) {
       return new FormulaExecutorComponentVisitor(this, formulas);
     }
   }
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/formula/coverage/CoverageVariationFormula.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/formula/coverage/CoverageVariationFormula.java
index 660cabe0308..3a1b1f68c81 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/formula/coverage/CoverageVariationFormula.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/formula/coverage/CoverageVariationFormula.java
@@ -37,7 +37,7 @@ public abstract class CoverageVariationFormula<T extends ElementsAndCoveredEleme
   @Override
   public Optional<Measure> createMeasure(T counter, CreateMeasureContext context) {
     LongValue elements = counter.elements;
-    if (elements.isSet() && elements.getValue() > 0d) {
+    if (elements.isSet() && elements.getValue() > 0D) {
       LongValue coveredElements = counter.coveredElements;
       double variation = calculateCoverage(coveredElements.getValue(), elements.getValue());
       return Optional.of(newMeasureBuilder().setVariation(variation).createNoValue());
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/issue/IssueLifecycle.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/issue/IssueLifecycle.java
index 5e8fb336ac0..430a1249d64 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/issue/IssueLifecycle.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/issue/IssueLifecycle.java
@@ -80,14 +80,14 @@ public class IssueLifecycle {
     setStatus(issue, rule);
   }
 
-  private void setType(DefaultIssue issue, Rule rule) {
+  private static void setType(DefaultIssue issue, Rule rule) {
     if (issue.isFromExternalRuleEngine()) {
       return;
     }
     issue.setType(requireNonNull(rule.getType(), "No rule type"));
   }
 
-  private void setStatus(DefaultIssue issue, Rule rule) {
+  private static void setStatus(DefaultIssue issue, Rule rule) {
     if (rule.getType() == RuleType.SECURITY_HOTSPOT || issue.type() == RuleType.SECURITY_HOTSPOT) {
       issue.setStatus(Issue.STATUS_TO_REVIEW);
     } else {
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/qualitymodel/MaintainabilityMeasuresVisitor.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/qualitymodel/MaintainabilityMeasuresVisitor.java
index 6fbd913fa33..23069a93062 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/qualitymodel/MaintainabilityMeasuresVisitor.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/qualitymodel/MaintainabilityMeasuresVisitor.java
@@ -112,9 +112,9 @@ public class MaintainabilityMeasuresVisitor extends PathAwareVisitorAdapter<Main
     Optional<Measure> measure = measureRepository.getRawMeasure(component, maintainabilityRemediationEffortMetric);
     double maintainabilityRemediationEffort = measure.isPresent() ? measure.get().getLongValue() : 0L;
     if (Double.doubleToRawLongBits(developmentCost.devCosts) != 0L) {
-      return maintainabilityRemediationEffort / (double) developmentCost.devCosts;
+      return maintainabilityRemediationEffort / developmentCost.devCosts;
     }
-    return 0d;
+    return 0D;
   }
 
   private void addDevelopmentCostMeasure(Component component, Counter developmentCost) {
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/qualitymodel/NewMaintainabilityMeasuresVisitor.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/qualitymodel/NewMaintainabilityMeasuresVisitor.java
index 9d7c3318c10..4e233e65e86 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/qualitymodel/NewMaintainabilityMeasuresVisitor.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/qualitymodel/NewMaintainabilityMeasuresVisitor.java
@@ -125,7 +125,7 @@ public class NewMaintainabilityMeasuresVisitor extends PathAwareVisitorAdapter<N
         return newDebt.getValue() / (double) developmentCost;
       }
     }
-    return 0d;
+    return 0D;
   }
 
   private static long getLongValue(Optional<Measure> measure) {
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/CommentMeasuresStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/CommentMeasuresStep.java
index 921fc7ea48a..748fe8e593a 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/CommentMeasuresStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/CommentMeasuresStep.java
@@ -52,7 +52,7 @@ public class CommentMeasuresStep implements ComputationStep {
   private final TreeRootHolder treeRootHolder;
   private final MetricRepository metricRepository;
   private final MeasureRepository measureRepository;
-  private final List<Formula> formulas;
+  private final List<Formula<?>> formulas;
 
   public CommentMeasuresStep(TreeRootHolder treeRootHolder, MetricRepository metricRepository, MeasureRepository measureRepository) {
     this.treeRootHolder = treeRootHolder;
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/ComplexityMeasuresStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/ComplexityMeasuresStep.java
index 52e5fe82577..09a8ee63461 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/ComplexityMeasuresStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/ComplexityMeasuresStep.java
@@ -48,7 +48,7 @@ import static org.sonar.ce.task.projectanalysis.formula.SumFormula.createIntSumF
  * Computes complexity measures on files and then aggregates them on higher components.
  */
 public class ComplexityMeasuresStep implements ComputationStep {
-  private static final List<Formula> FORMULAS = List.of(
+  private static final List<Formula<?>> FORMULAS = List.of(
     createIntSumFormula(COMPLEXITY_KEY),
     createIntSumFormula(COMPLEXITY_IN_CLASSES_KEY),
     createIntSumFormula(COMPLEXITY_IN_FUNCTIONS_KEY),
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/CoverageMeasuresStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/CoverageMeasuresStep.java
index ecaad9b10bd..76f5a84601d 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/CoverageMeasuresStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/CoverageMeasuresStep.java
@@ -55,7 +55,7 @@ import static org.sonar.ce.task.projectanalysis.formula.SumFormula.createIntSumF
  * Computes coverage measures on files and then aggregates them on higher components.
  */
 public class CoverageMeasuresStep implements ComputationStep {
-  private static final List<Formula> COVERAGE_FORMULAS = List.of(
+  private static final List<Formula<?>> COVERAGE_FORMULAS = List.of(
     createIntSumFormula(LINES_TO_COVER_KEY),
     createIntSumFormula(UNCOVERED_LINES_KEY),
     createIntSumFormula(CONDITIONS_TO_COVER_KEY),
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/LanguageDistributionMeasuresStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/LanguageDistributionMeasuresStep.java
index 5d858fac4ac..28cae0d9b0d 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/LanguageDistributionMeasuresStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/LanguageDistributionMeasuresStep.java
@@ -52,7 +52,7 @@ import static org.sonar.ce.task.projectanalysis.measure.Measure.newMeasureBuilde
 public class LanguageDistributionMeasuresStep implements ComputationStep {
   private static final String UNKNOWN_LANGUAGE_KEY = "<null>";
 
-  private static final List<Formula> FORMULAS = List.of(new LanguageDistributionFormula());
+  private static final List<Formula<?>> FORMULAS = List.of(new LanguageDistributionFormula());
 
   private static final String[] LANGUAGE_DISTRIBUTION_FORMULA_METRICS = new String[] {NCLOC_LANGUAGE_DISTRIBUTION_KEY};
 
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/NewCoverageMeasuresStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/NewCoverageMeasuresStep.java
index bbb6777d20a..c8a9f43b913 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/NewCoverageMeasuresStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/NewCoverageMeasuresStep.java
@@ -59,7 +59,7 @@ import static org.sonar.ce.task.projectanalysis.measure.Measure.newMeasureBuilde
  * Computes measures related to the New Coverage. These measures do not have values, only variations.
  */
 public class NewCoverageMeasuresStep implements ComputationStep {
-  private static final List<Formula> FORMULAS = List.of(
+  private static final List<Formula<?>> FORMULAS = List.of(
     // UT coverage
     new NewCoverageFormula(),
     new NewBranchCoverageFormula(),
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/NewSizeMeasuresStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/NewSizeMeasuresStep.java
index 8b49a05d829..c1c752a451e 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/NewSizeMeasuresStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/NewSizeMeasuresStep.java
@@ -106,7 +106,7 @@ public class NewSizeMeasuresStep implements ComputationStep {
         return;
       }
       Optional<Set<Integer>> changedLines = newLinesRepository.getNewLines(leaf);
-      if (!changedLines.isPresent()) {
+      if (changedLines.isEmpty()) {
         return;
       }
 
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/SizeMeasuresStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/SizeMeasuresStep.java
index b406c55fabe..535333ea6bb 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/SizeMeasuresStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/SizeMeasuresStep.java
@@ -19,8 +19,6 @@
  */
 package org.sonar.ce.task.projectanalysis.step;
 
-import java.util.Arrays;
-import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import org.sonar.ce.task.projectanalysis.component.Component;
@@ -53,13 +51,13 @@ import static org.sonar.ce.task.projectanalysis.measure.Measure.newMeasureBuilde
  */
 public class SizeMeasuresStep implements ComputationStep {
   private static final CounterStackElementFactory COUNTER_STACK_ELEMENT_FACTORY = new CounterStackElementFactory();
-  private static final List<Formula> AGGREGATED_SIZE_MEASURE_FORMULAS = Collections.unmodifiableList(Arrays.asList(
+  private static final List<Formula<?>> AGGREGATED_SIZE_MEASURE_FORMULAS = List.of(
     createIntSumFormula(GENERATED_LINES_KEY),
     createIntSumFormula(NCLOC_KEY),
     createIntSumFormula(GENERATED_NCLOC_KEY),
     createIntSumFormula(FUNCTIONS_KEY),
     createIntSumFormula(STATEMENTS_KEY),
-    createIntSumFormula(CLASSES_KEY)));
+    createIntSumFormula(CLASSES_KEY));
 
   private final TreeRootHolder treeRootHolder;
   private final MetricRepository metricRepository;
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/UnitTestMeasuresStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/UnitTestMeasuresStep.java
index 1dc926c495b..5eaad4e8738 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/UnitTestMeasuresStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectanalysis/step/UnitTestMeasuresStep.java
@@ -49,7 +49,7 @@ import static org.sonar.api.measures.CoreMetrics.TEST_SUCCESS_DENSITY_KEY;
 public class UnitTestMeasuresStep implements ComputationStep {
   private static final String[] METRICS = new String[] {TESTS_KEY, TEST_ERRORS_KEY, TEST_FAILURES_KEY, SKIPPED_TESTS_KEY, TEST_SUCCESS_DENSITY_KEY, TEST_EXECUTION_TIME_KEY};
 
-  private static final List<Formula> FORMULAS = List.of(new UnitTestsFormula());
+  private static final List<Formula<?>> FORMULAS = List.of(new UnitTestsFormula());
 
   private final TreeRootHolder treeRootHolder;
   private final MetricRepository metricRepository;
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectexport/issue/ExportIssuesStep.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectexport/issue/ExportIssuesStep.java
index 3d2b97c5f83..cec12aae7fa 100644
--- a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectexport/issue/ExportIssuesStep.java
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectexport/issue/ExportIssuesStep.java
@@ -32,6 +32,7 @@ import org.sonar.ce.task.projectexport.component.ComponentRepository;
 import org.sonar.ce.task.projectexport.rule.Rule;
 import org.sonar.ce.task.projectexport.rule.RuleRepository;
 import org.sonar.ce.task.projectexport.steps.DumpElement;
+import org.sonar.ce.task.projectexport.steps.DumpElement.IssueDumpElement;
 import org.sonar.ce.task.projectexport.steps.DumpWriter;
 import org.sonar.ce.task.projectexport.steps.ProjectHolder;
 import org.sonar.ce.task.projectexport.steps.StreamWriter;
@@ -134,8 +135,8 @@ public class ExportIssuesStep implements ComputationStep {
       .setResolution(emptyIfNull(rs, 11))
       .setSeverity(emptyIfNull(rs, 12))
       .setManualSeverity(rs.getBoolean(13))
-      .setGap(defaultIfNull(rs, 14, DumpElement.ISSUES.NO_GAP))
-      .setEffort(defaultIfNull(rs, 15, DumpElement.ISSUES.NO_EFFORT))
+      .setGap(defaultIfNull(rs, 14, IssueDumpElement.NO_GAP))
+      .setEffort(defaultIfNull(rs, 15, IssueDumpElement.NO_EFFORT))
       .setAssignee(emptyIfNull(rs, 16))
       .setAuthor(emptyIfNull(rs, 17))
       .setTags(emptyIfNull(rs, 18))
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectexport/taskprocessor/package-info.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectexport/taskprocessor/package-info.java
new file mode 100644
index 00000000000..6a335a9a35d
--- /dev/null
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/projectexport/taskprocessor/package-info.java
@@ -0,0 +1,23 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2021 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+@ParametersAreNonnullByDefault
+package org.sonar.ce.task.projectexport.taskprocessor;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/util/package-info.java b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/util/package-info.java
new file mode 100644
index 00000000000..279e6c3d071
--- /dev/null
+++ b/server/sonar-ce-task-projectanalysis/src/main/java/org/sonar/ce/task/util/package-info.java
@@ -0,0 +1,23 @@
+/*
+ * SonarQube
+ * Copyright (C) 2009-2021 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+@ParametersAreNonnullByDefault
+package org.sonar.ce.task.util;
+
+import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/api/measurecomputer/MeasureComputerDefinitionImplTest.java b/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/api/measurecomputer/MeasureComputerDefinitionImplTest.java
index e3465dc5108..5d2f612fc2f 100644
--- a/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/api/measurecomputer/MeasureComputerDefinitionImplTest.java
+++ b/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/api/measurecomputer/MeasureComputerDefinitionImplTest.java
@@ -153,13 +153,15 @@ public class MeasureComputerDefinitionImplTest {
       .setOutputMetrics("debt")
       .build();
 
-    assertThat(computer).isEqualTo(computer);
-    assertThat(computer).isEqualTo(sameComputer);
-    assertThat(computer).isNotEqualTo(anotherComputer);
-    assertThat(computer).isNotEqualTo(null);
+    assertThat(computer).isEqualTo(computer)
+      .isEqualTo(sameComputer)
+      .isNotEqualTo(anotherComputer)
+      .isNotEqualTo(null);
+
+    assertThat(computer)
+      .hasSameHashCodeAs(computer)
+      .hasSameHashCodeAs(sameComputer);
 
-    assertThat(computer.hashCode()).isEqualTo(computer.hashCode());
-    assertThat(computer.hashCode()).isEqualTo(sameComputer.hashCode());
     assertThat(computer.hashCode()).isNotEqualTo(anotherComputer.hashCode());
   }
 
@@ -169,7 +171,7 @@ public class MeasureComputerDefinitionImplTest {
       .setInputMetrics("ncloc", "comment")
       .setOutputMetrics("comment_density_1", "comment_density_2")
       .build().toString())
-        .isEqualTo("MeasureComputerDefinitionImpl{inputMetricKeys=[ncloc, comment], outputMetrics=[comment_density_1, comment_density_2]}");
+      .isEqualTo("MeasureComputerDefinitionImpl{inputMetricKeys=[ncloc, comment], outputMetrics=[comment_density_1, comment_density_2]}");
   }
 
 }
diff --git a/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/component/ComponentTreeBuilderTest.java b/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/component/ComponentTreeBuilderTest.java
index e6c55f1aab5..6d0a4de70d8 100644
--- a/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/component/ComponentTreeBuilderTest.java
+++ b/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/component/ComponentTreeBuilderTest.java
@@ -28,6 +28,7 @@ import java.util.Objects;
 import java.util.Optional;
 import java.util.Random;
 import java.util.function.Function;
+import java.util.function.UnaryOperator;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
@@ -56,7 +57,7 @@ public class ComponentTreeBuilderTest {
     + ComponentKeys.createEffectiveKey(projectKey, path);
   private static final ComponentKeyGenerator PUBLIC_KEY_GENERATOR = (projectKey, path) -> "public_"
     + ComponentKeys.createEffectiveKey(projectKey, path);
-  private static final Function<String, String> UUID_SUPPLIER = (componentKey) -> componentKey + "_uuid";
+  private static final UnaryOperator<String> UUID_SUPPLIER = (componentKey) -> componentKey + "_uuid";
   private static final EnumSet<ScannerReport.Component.ComponentType> REPORT_TYPES = EnumSet.of(PROJECT, FILE);
   private static final String NO_SCM_BASE_PATH = "";
   // both no project as "" or null should be supported
diff --git a/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/filemove/MatchTest.java b/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/filemove/MatchTest.java
index 35213625a34..31d85929675 100644
--- a/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/filemove/MatchTest.java
+++ b/server/sonar-ce-task-projectanalysis/src/test/java/org/sonar/ce/task/projectanalysis/filemove/MatchTest.java
@@ -52,23 +52,25 @@ public class MatchTest {
 
   @Test
   public void equals_is_based_on_both_properties() {
-    assertThat(underTest).isEqualTo(new Match(SOME_KEY, SOME_REPORT_KEY));
-    assertThat(underTest).isNotEqualTo(new Match("other key", SOME_REPORT_KEY));
-    assertThat(underTest).isNotEqualTo(new Match(SOME_KEY, "other report key"));
-    assertThat(underTest).isNotEqualTo(new Match(null, SOME_REPORT_KEY));
-    assertThat(underTest).isNotEqualTo(new Match(SOME_KEY, null));
-    assertThat(underTest).isNotEqualTo(new Match(null, null));
+    assertThat(underTest)
+      .isEqualTo(new Match(SOME_KEY, SOME_REPORT_KEY))
+      .isNotEqualTo(new Match("other key", SOME_REPORT_KEY))
+      .isNotEqualTo(new Match(SOME_KEY, "other report key"))
+      .isNotEqualTo(new Match(null, SOME_REPORT_KEY))
+      .isNotEqualTo(new Match(SOME_KEY, null))
+      .isNotEqualTo(new Match(null, null));
   }
 
   @Test
   public void hashcode_is_base_on_both_properties() {
     int hashCode = underTest.hashCode();
-    assertThat(hashCode).isEqualTo(new Match(SOME_KEY, SOME_REPORT_KEY).hashCode());
-    assertThat(hashCode).isNotEqualTo(new Match("other key", SOME_REPORT_KEY).hashCode());
-    assertThat(hashCode).isNotEqualTo(new Match(SOME_KEY, "other report key").hashCode());
-    assertThat(hashCode).isNotEqualTo(new Match(null, SOME_REPORT_KEY).hashCode());
-    assertThat(hashCode).isNotEqualTo(new Match(SOME_KEY, null).hashCode());
-    assertThat(hashCode).isNotEqualTo(new Match(null, null).hashCode());
+    assertThat(hashCode)
+      .isEqualTo(new Match(SOME_KEY, SOME_REPORT_KEY).hashCode())
+      .isNotEqualTo(new Match("other key", SOME_REPORT_KEY).hashCode())
+      .isNotEqualTo(new Match(SOME_KEY, "other report key").hashCode())
+      .isNotEqualTo(new Match(null, SOME_REPORT_KEY).hashCode())
+      .isNotEqualTo(new Match(SOME_KEY, null).hashCode())
+      .isNotEqualTo(new Match(null, null).hashCode());
   }
 
   @Test
diff --git a/server/sonar-db-core/src/main/java/org/sonar/db/DatabaseUtils.java b/server/sonar-db-core/src/main/java/org/sonar/db/DatabaseUtils.java
index d170870b844..4a74e8771a3 100644
--- a/server/sonar-db-core/src/main/java/org/sonar/db/DatabaseUtils.java
+++ b/server/sonar-db-core/src/main/java/org/sonar/db/DatabaseUtils.java
@@ -43,6 +43,7 @@ import java.util.Optional;
 import java.util.Set;
 import java.util.function.Consumer;
 import java.util.function.IntFunction;
+import java.util.function.IntSupplier;
 import java.util.function.Supplier;
 import java.util.regex.Pattern;
 import javax.annotation.CheckForNull;
@@ -440,10 +441,10 @@ public class DatabaseUtils {
   /**
    * This method can be used as a method reference, for not to have to handle the checked exception {@link SQLException}
    */
-  public static Consumer<String> setStrings(PreparedStatement stmt, Supplier<Integer> index) {
+  public static Consumer<String> setStrings(PreparedStatement stmt, IntSupplier index) {
     return value -> {
       try {
-        stmt.setString(index.get(), value);
+        stmt.setString(index.getAsInt(), value);
       } catch (SQLException e) {
         Throwables.propagate(e);
       }
diff --git a/server/sonar-server-common/src/main/java/org/sonar/server/config/ConfigurationProvider.java b/server/sonar-server-common/src/main/java/org/sonar/server/config/ConfigurationProvider.java
index 679a445d2a2..083c9ec8c4c 100644
--- a/server/sonar-server-common/src/main/java/org/sonar/server/config/ConfigurationProvider.java
+++ b/server/sonar-server-common/src/main/java/org/sonar/server/config/ConfigurationProvider.java
@@ -20,14 +20,14 @@
 package org.sonar.server.config;
 
 import java.util.Optional;
-import java.util.function.Function;
+import java.util.function.UnaryOperator;
 import org.apache.commons.lang.ArrayUtils;
 import org.picocontainer.injectors.ProviderAdapter;
 import org.sonar.api.config.Configuration;
 import org.sonar.api.config.PropertyDefinition;
 import org.sonar.api.config.internal.Settings;
 
-import static java.util.function.Function.identity;
+import static java.util.function.UnaryOperator.identity;
 import static org.sonar.api.config.internal.MultivalueProperty.parseAsCsv;
 
 public class ConfigurationProvider extends ProviderAdapter {
@@ -42,7 +42,7 @@ public class ConfigurationProvider extends ProviderAdapter {
   }
 
   private static class ServerConfigurationAdapter implements Configuration {
-    private static final Function<String, String> REPLACE_ENCODED_COMMAS = value -> value.replace("%2C", ",");
+    private static final UnaryOperator<String> REPLACE_ENCODED_COMMAS = value -> value.replace("%2C", ",");
 
     private final Settings settings;
 
diff --git a/server/sonar-server-common/src/main/java/org/sonar/server/es/SearchIdResult.java b/server/sonar-server-common/src/main/java/org/sonar/server/es/SearchIdResult.java
index 7b51418ffcd..0c5a4a36cfd 100644
--- a/server/sonar-server-common/src/main/java/org/sonar/server/es/SearchIdResult.java
+++ b/server/sonar-server-common/src/main/java/org/sonar/server/es/SearchIdResult.java
@@ -19,10 +19,10 @@
  */
 package org.sonar.server.es;
 
-import com.google.common.base.Function;
 import java.time.ZoneId;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Function;
 import org.apache.commons.lang.builder.ReflectionToStringBuilder;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.search.SearchHit;
diff --git a/server/sonar-server-common/src/main/java/org/sonar/server/es/textsearch/ComponentTextSearchFeatureRepertoire.java b/server/sonar-server-common/src/main/java/org/sonar/server/es/textsearch/ComponentTextSearchFeatureRepertoire.java
index 8a4cee79eb3..f3833a05319 100644
--- a/server/sonar-server-common/src/main/java/org/sonar/server/es/textsearch/ComponentTextSearchFeatureRepertoire.java
+++ b/server/sonar-server-common/src/main/java/org/sonar/server/es/textsearch/ComponentTextSearchFeatureRepertoire.java
@@ -60,7 +60,7 @@ public enum ComponentTextSearchFeatureRepertoire implements ComponentTextSearchF
         return Stream.empty();
       }
       BoolQueryBuilder queryBuilder = prefixAndPartialQuery(tokens, query.getFieldName(), SEARCH_PREFIX_ANALYZER)
-        .boost(3f);
+        .boost(3F);
       return Stream.of(queryBuilder);
     }
   },
diff --git a/server/sonar-server-common/src/main/java/org/sonar/server/qualitygate/ConditionEvaluator.java b/server/sonar-server-common/src/main/java/org/sonar/server/qualitygate/ConditionEvaluator.java
index 66f63e779ea..0c1e9d35ead 100644
--- a/server/sonar-server-common/src/main/java/org/sonar/server/qualitygate/ConditionEvaluator.java
+++ b/server/sonar-server-common/src/main/java/org/sonar/server/qualitygate/ConditionEvaluator.java
@@ -49,12 +49,12 @@ class ConditionEvaluator {
    */
   static EvaluatedCondition evaluate(Condition condition, QualityGateEvaluator.Measures measures) {
     Optional<QualityGateEvaluator.Measure> measure = measures.get(condition.getMetricKey());
-    if (!measure.isPresent()) {
+    if (measure.isEmpty()) {
       return new EvaluatedCondition(condition, EvaluationStatus.OK, null);
     }
 
     Optional<Comparable> value = getMeasureValue(condition, measure.get());
-    if (!value.isPresent()) {
+    if (value.isEmpty()) {
       return new EvaluatedCondition(condition, EvaluationStatus.OK, null);
     }
 
diff --git a/server/sonar-webserver-api/src/main/java/org/sonar/server/plugins/PluginJarLoader.java b/server/sonar-webserver-api/src/main/java/org/sonar/server/plugins/PluginJarLoader.java
index 7e0c6ffe610..951d6c4eb2c 100644
--- a/server/sonar-webserver-api/src/main/java/org/sonar/server/plugins/PluginJarLoader.java
+++ b/server/sonar-webserver-api/src/main/java/org/sonar/server/plugins/PluginJarLoader.java
@@ -21,7 +21,6 @@ package org.sonar.server.plugins;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Strings;
-import com.google.common.collect.ImmutableSet;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
@@ -55,7 +54,7 @@ public class PluginJarLoader {
   private static final Logger LOG = Loggers.get(PluginJarLoader.class);
 
   // List of plugins that are silently removed if installed
-  private static final Set<String> DEFAULT_BLACKLISTED_PLUGINS = ImmutableSet.of("scmactivity", "issuesreport", "genericcoverage");
+  private static final Set<String> DEFAULT_BLACKLISTED_PLUGINS = Set.of("scmactivity", "issuesreport", "genericcoverage");
   // List of plugins that should prevent the server to finish its startup
   private static final Set<String> FORBIDDEN_INCOMPATIBLE_PLUGINS = Set.of(
     "sqale", "report", "views", "authgithub", "authgitlab", "authbitbucket", "authsaml", "ldap", "scmgit", "scmsvn");
diff --git a/server/sonar-webserver-es/src/main/java/org/sonar/server/issue/index/IssueQuery.java b/server/sonar-webserver-es/src/main/java/org/sonar/server/issue/index/IssueQuery.java
index 16e0cafe927..d76d1f10e82 100644
--- a/server/sonar-webserver-es/src/main/java/org/sonar/server/issue/index/IssueQuery.java
+++ b/server/sonar-webserver-es/src/main/java/org/sonar/server/issue/index/IssueQuery.java
@@ -59,7 +59,7 @@ public class IssueQuery {
    */
   public static final String SORT_HOTSPOTS = "HOTSPOTS";
 
-  public static final Set<String> SORTS = ImmutableSet.of(SORT_BY_CREATION_DATE, SORT_BY_UPDATE_DATE, SORT_BY_CLOSE_DATE, SORT_BY_ASSIGNEE, SORT_BY_SEVERITY,
+  public static final Set<String> SORTS = Set.of(SORT_BY_CREATION_DATE, SORT_BY_UPDATE_DATE, SORT_BY_CLOSE_DATE, SORT_BY_ASSIGNEE, SORT_BY_SEVERITY,
     SORT_BY_STATUS, SORT_BY_FILE_LINE, SORT_HOTSPOTS);
 
   private final Collection<String> issueKeys;
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/badge/ws/SvgFormatter.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/badge/ws/SvgFormatter.java
index 1d731995f08..ad79fb745f3 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/badge/ws/SvgFormatter.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/badge/ws/SvgFormatter.java
@@ -52,7 +52,7 @@ class SvgFormatter {
     NumberFormat numericFormatter = DecimalFormat.getInstance(Locale.ENGLISH);
     numericFormatter.setMaximumFractionDigits(1);
     int power = (int) StrictMath.log10(value);
-    double valueToFormat = value / (Math.pow(10, Math.floorDiv(power, 3) * 3d));
+    double valueToFormat = value / (Math.pow(10, Math.floorDiv(power, 3) * 3D));
     String formattedNumber = numericFormatter.format(valueToFormat);
     formattedNumber = formattedNumber + NUMERIC_SUFFIX_LIST.charAt(power / 3);
     return formattedNumber.length() > 4 ? trim(formattedNumber.replaceAll(NUMERIC_REGEXP, "")) : trim(formattedNumber);
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/component/ws/ComponentDtoToWsComponent.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/component/ws/ComponentDtoToWsComponent.java
index 96870a533e4..f64c83bdf39 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/component/ws/ComponentDtoToWsComponent.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/component/ws/ComponentDtoToWsComponent.java
@@ -19,7 +19,6 @@
  */
 package org.sonar.server.component.ws;
 
-import com.google.common.collect.ImmutableSet;
 import java.util.Arrays;
 import java.util.Set;
 import javax.annotation.Nullable;
@@ -39,7 +38,7 @@ class ComponentDtoToWsComponent {
   /**
    * The concept of "visibility" will only be configured for these qualifiers.
    */
-  private static final Set<String> QUALIFIERS_WITH_VISIBILITY = ImmutableSet.of(Qualifiers.PROJECT, Qualifiers.VIEW, Qualifiers.APP);
+  private static final Set<String> QUALIFIERS_WITH_VISIBILITY = Set.of(Qualifiers.PROJECT, Qualifiers.VIEW, Qualifiers.APP);
 
   private ComponentDtoToWsComponent() {
     // prevent instantiation
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/component/ws/TreeAction.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/component/ws/TreeAction.java
index 2fe046f363c..a9c8b5ec9db 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/component/ws/TreeAction.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/component/ws/TreeAction.java
@@ -93,6 +93,7 @@ public class TreeAction implements ComponentsWsAction {
   private static final String PATH_SORT = "path";
   private static final String QUALIFIER_SORT = "qualifier";
   private static final Set<String> SORTS = ImmutableSortedSet.of(NAME_SORT, PATH_SORT, QUALIFIER_SORT);
+  private static final Set<String> PROJECT_OR_APP_QUALIFIERS = ImmutableSortedSet.of(Qualifiers.PROJECT, Qualifiers.APP);
 
   private final DbClient dbClient;
   private final ComponentFinder componentFinder;
@@ -100,8 +101,6 @@ public class TreeAction implements ComponentsWsAction {
   private final UserSession userSession;
   private final I18n i18n;
 
-  private static final Set<String> PROJECT_OR_APP_QUALIFIERS = ImmutableSortedSet.of(Qualifiers.PROJECT, Qualifiers.APP);
-
   public TreeAction(DbClient dbClient, ComponentFinder componentFinder, ResourceTypes resourceTypes, UserSession userSession, I18n i18n) {
     this.dbClient = dbClient;
     this.componentFinder = componentFinder;
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/issue/ws/AuthorsAction.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/issue/ws/AuthorsAction.java
index 150d3333e31..94a8ab9dbac 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/issue/ws/AuthorsAction.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/issue/ws/AuthorsAction.java
@@ -63,8 +63,7 @@ public class AuthorsAction implements IssuesWsAction {
   private final ComponentFinder componentFinder;
 
   public AuthorsAction(UserSession userSession, DbClient dbClient, IssueIndex issueIndex,
-    IssueIndexSyncProgressChecker issueIndexSyncProgressChecker,
-    ComponentFinder componentFinder) {
+    IssueIndexSyncProgressChecker issueIndexSyncProgressChecker, ComponentFinder componentFinder) {
     this.userSession = userSession;
     this.dbClient = dbClient;
     this.issueIndex = issueIndex;
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/measure/live/MeasureMatrix.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/measure/live/MeasureMatrix.java
index ab5cf0a14e8..ffa64caf5ca 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/measure/live/MeasureMatrix.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/measure/live/MeasureMatrix.java
@@ -31,6 +31,7 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Function;
+import java.util.function.Predicate;
 import java.util.stream.Stream;
 import javax.annotation.Nullable;
 import org.sonar.db.component.ComponentDto;
@@ -152,7 +153,7 @@ class MeasureMatrix {
       .map(MeasureCell::getMeasure);
   }
 
-  private void changeCell(ComponentDto component, String metricKey, Function<LiveMeasureDto, Boolean> changer) {
+  private void changeCell(ComponentDto component, String metricKey, Predicate<LiveMeasureDto> changer) {
     MeasureCell cell = table.get(component.uuid(), metricKey);
     if (cell == null) {
       LiveMeasureDto measure = new LiveMeasureDto()
@@ -161,8 +162,8 @@ class MeasureMatrix {
         .setMetricUuid(metricsByKeys.get(metricKey).getUuid());
       cell = new MeasureCell(measure, true);
       table.put(component.uuid(), metricKey, cell);
-      changer.apply(cell.getMeasure());
-    } else if (changer.apply(cell.getMeasure())) {
+      changer.test(cell.getMeasure());
+    } else if (changer.test(cell.getMeasure())) {
       cell.setChanged(true);
     }
   }
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/permission/DefaultTemplatesResolverImpl.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/permission/DefaultTemplatesResolverImpl.java
index 763e27ac601..d42e43c90db 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/permission/DefaultTemplatesResolverImpl.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/permission/DefaultTemplatesResolverImpl.java
@@ -58,14 +58,14 @@ public class DefaultTemplatesResolverImpl implements DefaultTemplatesResolver {
     return resourceTypes.getRoots()
       .stream()
       .map(ResourceType::getQualifier)
-      .anyMatch(qualifier -> Qualifiers.VIEW.equals(qualifier));
+      .anyMatch(Qualifiers.VIEW::equals);
   }
 
   private static boolean isApplicationEnabled(ResourceTypes resourceTypes) {
     return resourceTypes.getRoots()
             .stream()
             .map(ResourceType::getQualifier)
-            .anyMatch(qualifier ->  Qualifiers.APP.equals(qualifier));
+            .anyMatch(Qualifiers.APP::equals);
   }
 
 }
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projectanalysis/ws/EventValidator.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projectanalysis/ws/EventValidator.java
index 80720fb319d..09cba422b81 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projectanalysis/ws/EventValidator.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projectanalysis/ws/EventValidator.java
@@ -33,7 +33,7 @@ import static org.sonar.server.projectanalysis.ws.EventCategory.VERSION;
 import static org.sonar.server.projectanalysis.ws.EventCategory.fromLabel;
 
 class EventValidator {
-  private static final Set<String> AUTHORIZED_CATEGORIES = ImmutableSet.of(VERSION.name(), OTHER.name());
+  private static final Set<String> AUTHORIZED_CATEGORIES = Set.of(VERSION.name(), OTHER.name());
   private static final String AUTHORIZED_CATEGORIES_INLINED = Joiner.on(", ").join(AUTHORIZED_CATEGORIES);
 
   private EventValidator() {
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projectlink/ws/CreateAction.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projectlink/ws/CreateAction.java
index 286746722e6..3faa0284081 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projectlink/ws/CreateAction.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projectlink/ws/CreateAction.java
@@ -44,15 +44,15 @@ import static org.sonar.server.ws.KeyExamples.KEY_PROJECT_EXAMPLE_001;
 import static org.sonar.server.ws.WsUtils.writeProtobuf;
 
 public class CreateAction implements ProjectLinksWsAction {
+  private static final int LINK_NAME_MAX_LENGTH = 128;
+  private static final int LINK_URL_MAX_LENGTH = 2048;
+  private static final int LINK_TYPE_MAX_LENGTH = 20;
+
   private final DbClient dbClient;
   private final UserSession userSession;
   private final ComponentFinder componentFinder;
   private final UuidFactory uuidFactory;
 
-  private static final int LINK_NAME_MAX_LENGTH = 128;
-  private static final int LINK_URL_MAX_LENGTH = 2048;
-  private static final int LINK_TYPE_MAX_LENGTH = 20;
-
   public CreateAction(DbClient dbClient, UserSession userSession, ComponentFinder componentFinder, UuidFactory uuidFactory) {
     this.dbClient = dbClient;
     this.userSession = userSession;
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projecttag/TagsWsSupport.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projecttag/TagsWsSupport.java
index c5068931069..f5199a42234 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projecttag/TagsWsSupport.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/projecttag/TagsWsSupport.java
@@ -38,6 +38,11 @@ import static org.sonar.server.es.ProjectIndexer.Cause.PROJECT_TAGS_UPDATE;
 import static org.sonar.server.exceptions.BadRequestException.checkRequest;
 
 public class TagsWsSupport {
+  /**
+   * The characters allowed in project tags are lower-case
+   * letters, digits, plus (+), sharp (#), dash (-) and dot (.)
+   */
+  private static final Pattern VALID_TAG_REGEXP = Pattern.compile("[a-z0-9+#\\-.]+$");
 
   private final DbClient dbClient;
   private final ComponentFinder componentFinder;
@@ -45,12 +50,6 @@ public class TagsWsSupport {
   private final ProjectIndexers projectIndexers;
   private final System2 system2;
 
-  /**
-   * The characters allowed in project tags are lower-case
-   * letters, digits, plus (+), sharp (#), dash (-) and dot (.)
-   */
-  private static final Pattern VALID_TAG_REGEXP = Pattern.compile("[a-z0-9+#\\-.]+$");
-
   public TagsWsSupport(DbClient dbClient, ComponentFinder componentFinder, UserSession userSession, ProjectIndexers projectIndexers, System2 system2) {
     this.dbClient = dbClient;
     this.componentFinder = componentFinder;
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/qualitygate/QualityGateConditionsUpdater.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/qualitygate/QualityGateConditionsUpdater.java
index 17363d18505..5f9447bc103 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/qualitygate/QualityGateConditionsUpdater.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/qualitygate/QualityGateConditionsUpdater.java
@@ -19,8 +19,6 @@
  */
 package org.sonar.server.qualitygate;
 
-import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableSet;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.EnumSet;
@@ -61,13 +59,12 @@ import static org.sonar.server.qualitygate.Condition.Operator.LESS_THAN;
 import static org.sonar.server.qualitygate.ValidRatingMetrics.isCoreRatingMetric;
 
 public class QualityGateConditionsUpdater {
-  public static final Set<String> INVALID_METRIC_KEYS = ImmutableSet.of(ALERT_STATUS_KEY, SECURITY_HOTSPOTS_KEY, NEW_SECURITY_HOTSPOTS_KEY);
+  public static final Set<String> INVALID_METRIC_KEYS = Set.of(ALERT_STATUS_KEY, SECURITY_HOTSPOTS_KEY, NEW_SECURITY_HOTSPOTS_KEY);
 
-  private static final Map<Integer, ImmutableSet<Condition.Operator>> VALID_OPERATORS_BY_DIRECTION = ImmutableMap.<Integer, ImmutableSet<Condition.Operator>>builder()
-    .put(DIRECTION_NONE, ImmutableSet.of(GREATER_THAN, LESS_THAN))
-    .put(DIRECTION_BETTER, ImmutableSet.of(LESS_THAN))
-    .put(DIRECTION_WORST, ImmutableSet.of(GREATER_THAN))
-    .build();
+  private static final Map<Integer, Set<Condition.Operator>> VALID_OPERATORS_BY_DIRECTION = Map.of(
+    DIRECTION_NONE, Set.of(GREATER_THAN, LESS_THAN),
+    DIRECTION_BETTER, Set.of(LESS_THAN),
+    DIRECTION_WORST, Set.of(GREATER_THAN));
 
   private static final EnumSet<ValueType> VALID_METRIC_TYPES = EnumSet.of(
     ValueType.INT,
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/setting/ws/SettingValidations.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/setting/ws/SettingValidations.java
index 42518606112..2f628b66c8f 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/setting/ws/SettingValidations.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/setting/ws/SettingValidations.java
@@ -19,10 +19,8 @@
  */
 package org.sonar.server.setting.ws;
 
-import com.google.common.collect.ImmutableSet;
 import com.google.gson.Gson;
 import com.google.gson.JsonElement;
-
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Collection;
@@ -34,7 +32,6 @@ import java.util.function.Consumer;
 import java.util.stream.Collectors;
 import javax.annotation.CheckForNull;
 import javax.annotation.Nullable;
-
 import org.everit.json.schema.ValidationException;
 import org.everit.json.schema.loader.SchemaLoader;
 import org.json.JSONObject;
@@ -64,6 +61,8 @@ public class SettingValidations {
     "sonar.security.config.pythonsecurity",
     "sonar.security.config.roslyn.sonaranalyzer.security.cs"
   );
+  private static final Set<String> SUPPORTED_QUALIFIERS = Set.of(Qualifiers.PROJECT, Qualifiers.VIEW, Qualifiers.APP, Qualifiers.MODULE, Qualifiers.SUBVIEW);
+
   private final PropertyDefinitions definitions;
   private final DbClient dbClient;
   private final I18n i18n;
@@ -82,8 +81,6 @@ public class SettingValidations {
     };
   }
 
-  private static final Set<String> SUPPORTED_QUALIFIERS = ImmutableSet.of(Qualifiers.PROJECT, Qualifiers.VIEW, Qualifiers.APP, Qualifiers.MODULE, Qualifiers.SUBVIEW);
-
   public Consumer<SettingData> qualifier() {
     return data -> {
       String qualifier = data.component == null ? "" : data.component.qualifier();
diff --git a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/ui/ws/ComponentAction.java b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/ui/ws/ComponentAction.java
index 2a04a40ae05..521d9aa52a4 100644
--- a/server/sonar-webserver-webapi/src/main/java/org/sonar/server/ui/ws/ComponentAction.java
+++ b/server/sonar-webserver-webapi/src/main/java/org/sonar/server/ui/ws/ComponentAction.java
@@ -19,7 +19,6 @@
  */
 package org.sonar.server.ui.ws;
 
-import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
 import java.util.Date;
 import java.util.List;
@@ -78,7 +77,7 @@ import static org.sonar.server.ws.KeyExamples.KEY_PULL_REQUEST_EXAMPLE_001;
 
 public class ComponentAction implements NavigationWsAction {
 
-  private static final Set<String> MODULE_OR_DIR_QUALIFIERS = ImmutableSet.of(Qualifiers.MODULE, Qualifiers.DIRECTORY);
+  private static final Set<String> MODULE_OR_DIR_QUALIFIERS = Set.of(Qualifiers.MODULE, Qualifiers.DIRECTORY);
   static final String PARAM_COMPONENT = "component";
   private static final String PARAM_BRANCH = "branch";
   private static final String PARAM_PULL_REQUEST = "pullRequest";
@@ -90,7 +89,7 @@ public class ComponentAction implements NavigationWsAction {
   /**
    * The concept of "visibility" will only be configured for these qualifiers.
    */
-  private static final Set<String> QUALIFIERS_WITH_VISIBILITY = ImmutableSet.of(Qualifiers.PROJECT, Qualifiers.VIEW, Qualifiers.APP);
+  private static final Set<String> QUALIFIERS_WITH_VISIBILITY = Set.of(Qualifiers.PROJECT, Qualifiers.VIEW, Qualifiers.APP);
 
   private final DbClient dbClient;
   private final PageRepository pageRepository;
diff --git a/server/sonar-webserver-webapi/src/test/java/org/sonar/server/projectanalysis/ws/UpdateEventActionTest.java b/server/sonar-webserver-webapi/src/test/java/org/sonar/server/projectanalysis/ws/UpdateEventActionTest.java
index 332ac7b5878..2fc92bed1fd 100644
--- a/server/sonar-webserver-webapi/src/test/java/org/sonar/server/projectanalysis/ws/UpdateEventActionTest.java
+++ b/server/sonar-webserver-webapi/src/test/java/org/sonar/server/projectanalysis/ws/UpdateEventActionTest.java
@@ -61,9 +61,9 @@ public class UpdateEventActionTest {
   @Rule
   public DbTester db = DbTester.create(System2.INSTANCE);
 
-  private DbClient dbClient = db.getDbClient();
-  private DbSession dbSession = db.getSession();
-  private WsActionTester ws = new WsActionTester(new UpdateEventAction(dbClient, userSession));
+  private final DbClient dbClient = db.getDbClient();
+  private final DbSession dbSession = db.getSession();
+  private final WsActionTester ws = new WsActionTester(new UpdateEventAction(dbClient, userSession));
 
   @Test
   public void json_example() {
diff --git a/server/sonar-webserver-ws/src/main/java/org/sonar/server/ws/ServletRequest.java b/server/sonar-webserver-ws/src/main/java/org/sonar/server/ws/ServletRequest.java
index 232dccd3ce1..b24609ed5dd 100644
--- a/server/sonar-webserver-ws/src/main/java/org/sonar/server/ws/ServletRequest.java
+++ b/server/sonar-webserver-ws/src/main/java/org/sonar/server/ws/ServletRequest.java
@@ -43,14 +43,13 @@ import static org.apache.commons.lang.StringUtils.substringAfterLast;
 import static org.apache.tomcat.util.http.fileupload.FileUploadBase.MULTIPART;
 
 public class ServletRequest extends ValidatingRequest {
-
-  private final HttpServletRequest source;
-
   static final Map<String, String> SUPPORTED_MEDIA_TYPES_BY_URL_SUFFIX = ImmutableMap.of(
     "json", MediaTypes.JSON,
     "protobuf", MediaTypes.PROTOBUF,
     "text", MediaTypes.TXT);
 
+  private final HttpServletRequest source;
+
   public ServletRequest(HttpServletRequest source) {
     this.source = source;
   }
diff --git a/server/sonar-webserver/src/main/java/org/sonar/server/platform/web/SecurityServletFilter.java b/server/sonar-webserver/src/main/java/org/sonar/server/platform/web/SecurityServletFilter.java
index e6acde64f5d..4ebd2a36a92 100644
--- a/server/sonar-webserver/src/main/java/org/sonar/server/platform/web/SecurityServletFilter.java
+++ b/server/sonar-webserver/src/main/java/org/sonar/server/platform/web/SecurityServletFilter.java
@@ -19,7 +19,6 @@
  */
 package org.sonar.server.platform.web;
 
-import com.google.common.collect.ImmutableSet;
 import java.io.IOException;
 import java.util.Set;
 import javax.servlet.Filter;
@@ -36,7 +35,7 @@ import javax.servlet.http.HttpServletResponse;
  */
 public class SecurityServletFilter implements Filter {
 
-  private static final Set<String> ALLOWED_HTTP_METHODS = ImmutableSet.of("DELETE", "GET", "HEAD", "POST", "PUT");
+  private static final Set<String> ALLOWED_HTTP_METHODS = Set.of("DELETE", "GET", "HEAD", "POST", "PUT");
 
   @Override
   public void init(FilterConfig filterConfig) {
diff --git a/sonar-core/src/main/java/org/sonar/core/extension/CoreExtensionsInstaller.java b/sonar-core/src/main/java/org/sonar/core/extension/CoreExtensionsInstaller.java
index 41fa24cd5e0..86b242ef449 100644
--- a/sonar-core/src/main/java/org/sonar/core/extension/CoreExtensionsInstaller.java
+++ b/sonar-core/src/main/java/org/sonar/core/extension/CoreExtensionsInstaller.java
@@ -41,6 +41,13 @@ public abstract class CoreExtensionsInstaller {
   private final CoreExtensionRepository coreExtensionRepository;
   private final Class<? extends Annotation> supportedAnnotationType;
 
+  protected CoreExtensionsInstaller(SonarRuntime sonarRuntime, CoreExtensionRepository coreExtensionRepository,
+    Class<? extends Annotation> supportedAnnotationType) {
+    this.sonarRuntime = sonarRuntime;
+    this.coreExtensionRepository = coreExtensionRepository;
+    this.supportedAnnotationType = supportedAnnotationType;
+  }
+
   public static Predicate<Object> noExtensionFilter() {
     return t -> true;
   }
@@ -49,13 +56,6 @@ public abstract class CoreExtensionsInstaller {
     return t -> true;
   }
 
-  protected CoreExtensionsInstaller(SonarRuntime sonarRuntime, CoreExtensionRepository coreExtensionRepository,
-    Class<? extends Annotation> supportedAnnotationType) {
-    this.sonarRuntime = sonarRuntime;
-    this.coreExtensionRepository = coreExtensionRepository;
-    this.supportedAnnotationType = supportedAnnotationType;
-  }
-
   /**
    * @param container            the container into which extensions will be installed
    * @param extensionFilter      filters extensions added to {@link CoreExtension.Context}. When it returns false, the
diff --git a/sonar-duplications/src/main/java/org/sonar/duplications/block/Block.java b/sonar-duplications/src/main/java/org/sonar/duplications/block/Block.java
index 012a71cf976..1017c4649c4 100644
--- a/sonar-duplications/src/main/java/org/sonar/duplications/block/Block.java
+++ b/sonar-duplications/src/main/java/org/sonar/duplications/block/Block.java
@@ -32,14 +32,26 @@ public final class Block {
   private final int startLine;
   private final int endLine;
 
-  private int startUnit;
-  private int endUnit;
+  private final int startUnit;
+  private final int endUnit;
 
   /**
    * Cache for hash code.
    */
   private int hash;
 
+  private Block(Builder builder) {
+    this.resourceId = builder.resourceId;
+    this.blockHash = builder.blockHash;
+    this.indexInFile = builder.indexInFile;
+
+    this.startLine = builder.startLine;
+    this.endLine = builder.endLine;
+
+    this.startUnit = builder.startUnit;
+    this.endUnit = builder.endUnit;
+  }
+
   /**
    * @since 2.14
    */
@@ -97,18 +109,6 @@ public final class Block {
     }
   }
 
-  private Block(Builder builder) {
-    this.resourceId = builder.resourceId;
-    this.blockHash = builder.blockHash;
-    this.indexInFile = builder.indexInFile;
-
-    this.startLine = builder.startLine;
-    this.endLine = builder.endLine;
-
-    this.startUnit = builder.startUnit;
-    this.endUnit = builder.endUnit;
-  }
-
   public String getHashHex() {
     return getBlockHash().toString();
   }
diff --git a/sonar-duplications/src/main/java/org/sonar/duplications/block/ByteArray.java b/sonar-duplications/src/main/java/org/sonar/duplications/block/ByteArray.java
index 2cb7546fd50..306a91dff6a 100644
--- a/sonar-duplications/src/main/java/org/sonar/duplications/block/ByteArray.java
+++ b/sonar-duplications/src/main/java/org/sonar/duplications/block/ByteArray.java
@@ -30,6 +30,7 @@ import java.util.Arrays;
  * also maybe we can incorporate it into Block to reduce memory footprint during detection of duplicates
  */
 public final class ByteArray {
+  private static final String HEXES = "0123456789abcdef";
 
   private final byte[] bytes;
 
@@ -103,8 +104,6 @@ public final class ByteArray {
     return result;
   }
 
-  private static final String HEXES = "0123456789abcdef";
-
   public String toHexString() {
     StringBuilder hex = new StringBuilder(2 * bytes.length);
     for (byte b : bytes) {
diff --git a/sonar-duplications/src/main/java/org/sonar/duplications/detector/original/BlocksGroup.java b/sonar-duplications/src/main/java/org/sonar/duplications/detector/original/BlocksGroup.java
index 65e182b11eb..dd142833c4c 100644
--- a/sonar-duplications/src/main/java/org/sonar/duplications/detector/original/BlocksGroup.java
+++ b/sonar-duplications/src/main/java/org/sonar/duplications/detector/original/BlocksGroup.java
@@ -30,8 +30,13 @@ import org.sonar.duplications.utils.FastStringComparator;
  * Set of {@link Block}s, which internally stored as a sorted list.
  */
 final class BlocksGroup {
+  private static final Comparator<String> RESOURCE_ID_COMPARATOR = FastStringComparator.INSTANCE;
   final List<Block> blocks;
 
+  private BlocksGroup() {
+    this.blocks = new ArrayList<>();
+  }
+
   /**
    * Factory method.
    *
@@ -41,10 +46,6 @@ final class BlocksGroup {
     return new BlocksGroup();
   }
 
-  private BlocksGroup() {
-    this.blocks = new ArrayList<>();
-  }
-
   public int size() {
     return blocks.size();
   }
@@ -193,8 +194,6 @@ final class BlocksGroup {
     return result;
   }
 
-  private static final Comparator<String> RESOURCE_ID_COMPARATOR = FastStringComparator.INSTANCE;
-
   /**
    * Compares {@link Block}s first using {@link Block#getResourceId() resource id} and then using {@link Block#getIndexInFile() index in file}.
    */
diff --git a/sonar-duplications/src/main/java/org/sonar/duplications/detector/suffixtree/TextSet.java b/sonar-duplications/src/main/java/org/sonar/duplications/detector/suffixtree/TextSet.java
index ecb687e36d8..5d01ee6c9b9 100644
--- a/sonar-duplications/src/main/java/org/sonar/duplications/detector/suffixtree/TextSet.java
+++ b/sonar-duplications/src/main/java/org/sonar/duplications/detector/suffixtree/TextSet.java
@@ -21,7 +21,6 @@ package org.sonar.duplications.detector.suffixtree;
 
 import java.util.ArrayList;
 import java.util.List;
-
 import org.sonar.duplications.block.Block;
 
 
@@ -29,10 +28,15 @@ import org.sonar.duplications.block.Block;
  * Simplifies construction of <a href="http://en.wikipedia.org/wiki/Generalised_suffix_tree">generalised suffix-tree</a>.
  */
 public final class TextSet extends AbstractText {
+  private final int lengthOfOrigin;
 
+  private TextSet(List<Object> symbols, int lengthOfOrigin) {
+    super(symbols);
+    this.lengthOfOrigin = lengthOfOrigin;
+  }
   public static final class Builder {
 
-    private List<Object> symbols = new ArrayList<>();
+    private final List<Object> symbols = new ArrayList<>();
     private Integer lengthOfOrigin;
     private int count;
 
@@ -58,13 +62,6 @@ public final class TextSet extends AbstractText {
     return new Builder();
   }
 
-  private final int lengthOfOrigin;
-
-  private TextSet(List<Object> symbols, int lengthOfOrigin) {
-    super(symbols);
-    this.lengthOfOrigin = lengthOfOrigin;
-  }
-
   public boolean isInsideOrigin(int pos) {
     return pos < lengthOfOrigin;
   }
@@ -100,15 +97,9 @@ public final class TextSet extends AbstractText {
       return stringNumber;
     }
 
-    public int getStringNumber() {
-      return stringNumber;
-    }
-
     @Override
     public String toString() {
       return "$" + stringNumber;
     }
-
   }
-
 }
diff --git a/sonar-plugin-api-impl/src/main/java/org/sonar/api/config/internal/MultivalueProperty.java b/sonar-plugin-api-impl/src/main/java/org/sonar/api/config/internal/MultivalueProperty.java
index 41473a7f91e..338aca11c34 100644
--- a/sonar-plugin-api-impl/src/main/java/org/sonar/api/config/internal/MultivalueProperty.java
+++ b/sonar-plugin-api-impl/src/main/java/org/sonar/api/config/internal/MultivalueProperty.java
@@ -25,21 +25,24 @@ import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import java.util.function.Function;
+import java.util.function.UnaryOperator;
 import org.apache.commons.csv.CSVFormat;
 import org.apache.commons.csv.CSVParser;
 import org.apache.commons.csv.CSVRecord;
 import org.apache.commons.lang.ArrayUtils;
 
+import static java.util.function.UnaryOperator.identity;
+
 public class MultivalueProperty {
   private MultivalueProperty() {
     // prevents instantiation
   }
 
   public static String[] parseAsCsv(String key, String value) {
-    return parseAsCsv(key, value, Function.identity());
+    return parseAsCsv(key, value, identity());
   }
 
-  public static String[] parseAsCsv(String key, String value, Function<String, String> valueProcessor) {
+  public static String[] parseAsCsv(String key, String value, UnaryOperator<String> valueProcessor) {
     String cleanValue = MultivalueProperty.trimFieldsAndRemoveEmptyFields(value);
     List<String> result = new ArrayList<>();
     try (CSVParser csvParser = CSVFormat.RFC4180
diff --git a/sonar-plugin-api-impl/src/main/java/org/sonar/api/impl/server/RulesDefinitionContext.java b/sonar-plugin-api-impl/src/main/java/org/sonar/api/impl/server/RulesDefinitionContext.java
index 90140b89905..437af08e5ec 100644
--- a/sonar-plugin-api-impl/src/main/java/org/sonar/api/impl/server/RulesDefinitionContext.java
+++ b/sonar-plugin-api-impl/src/main/java/org/sonar/api/impl/server/RulesDefinitionContext.java
@@ -58,6 +58,7 @@ public class RulesDefinitionContext extends RulesDefinition.Context {
     return unmodifiableList(new ArrayList<>(repositoriesByKey.values()));
   }
 
+  @Override
   public void registerRepository(DefaultNewRepository newRepository) {
     RulesDefinition.Repository existing = repositoriesByKey.get(newRepository.key());
     if (existing != null) {
@@ -69,6 +70,7 @@ public class RulesDefinitionContext extends RulesDefinition.Context {
     repositoriesByKey.put(newRepository.key(), new DefaultRepository(newRepository, existing));
   }
 
+  @Override
   public String currentPluginKey() {
     return currentPluginKey;
   }
diff --git a/sonar-plugin-api-impl/src/main/java/org/sonar/api/impl/utils/AlwaysIncreasingSystem2.java b/sonar-plugin-api-impl/src/main/java/org/sonar/api/impl/utils/AlwaysIncreasingSystem2.java
index c0fb5b70b87..70a895ba4fd 100644
--- a/sonar-plugin-api-impl/src/main/java/org/sonar/api/impl/utils/AlwaysIncreasingSystem2.java
+++ b/sonar-plugin-api-impl/src/main/java/org/sonar/api/impl/utils/AlwaysIncreasingSystem2.java
@@ -21,7 +21,7 @@ package org.sonar.api.impl.utils;
 
 import java.security.SecureRandom;
 import java.util.concurrent.atomic.AtomicLong;
-import java.util.function.Supplier;
+import java.util.function.LongSupplier;
 import org.sonar.api.utils.System2;
 
 import static org.sonar.api.utils.Preconditions.checkArgument;
@@ -38,9 +38,9 @@ public class AlwaysIncreasingSystem2 extends System2 {
   private final AtomicLong now;
   private final long increment;
 
-  private AlwaysIncreasingSystem2(Supplier<Long> initialValueSupplier, long increment) {
+  private AlwaysIncreasingSystem2(LongSupplier initialValueSupplier, long increment) {
     checkArgument(increment > 0, "increment must be > 0");
-    long initialValue = initialValueSupplier.get();
+    long initialValue = initialValueSupplier.getAsLong();
     checkArgument(initialValue >= 0, "Initial value must be >= 0");
     this.now = new AtomicLong(initialValue);
     this.increment = increment;
diff --git a/sonar-plugin-api-impl/src/test/java/org/sonar/api/config/internal/MultivaluePropertyTest.java b/sonar-plugin-api-impl/src/test/java/org/sonar/api/config/internal/MultivaluePropertyTest.java
index dff864dbd64..9ac4bedc574 100644
--- a/sonar-plugin-api-impl/src/test/java/org/sonar/api/config/internal/MultivaluePropertyTest.java
+++ b/sonar-plugin-api-impl/src/test/java/org/sonar/api/config/internal/MultivaluePropertyTest.java
@@ -23,12 +23,12 @@ import com.tngtech.java.junit.dataprovider.DataProvider;
 import com.tngtech.java.junit.dataprovider.DataProviderRunner;
 import com.tngtech.java.junit.dataprovider.UseDataProvider;
 import java.util.Random;
-import java.util.function.Function;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 
+import static java.util.function.UnaryOperator.identity;
 import static org.apache.commons.lang.RandomStringUtils.randomAlphanumeric;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.sonar.api.config.internal.MultivalueProperty.parseAsCsv;
@@ -46,7 +46,7 @@ public class MultivaluePropertyTest {
   public void parseAsCsv_for_coverage(String value, String[] expected) {
     // parseAsCsv is extensively tested in org.sonar.server.config.ConfigurationProviderTest
     assertThat(parseAsCsv("key", value))
-      .isEqualTo(parseAsCsv("key", value, Function.identity()))
+      .isEqualTo(parseAsCsv("key", value, identity()))
       .isEqualTo(expected);
   }
 
diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/batch/rule/Checks.java b/sonar-plugin-api/src/main/java/org/sonar/api/batch/rule/Checks.java
index 360488d1085..36672205968 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/batch/rule/Checks.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/batch/rule/Checks.java
@@ -109,7 +109,7 @@ public class Checks<C> {
   }
 
   public Checks<C> addAnnotatedChecks(Object... checkClassesOrObjects) {
-    return addAnnotatedChecks((Iterable) Arrays.asList(checkClassesOrObjects));
+    return addAnnotatedChecks(Arrays.asList(checkClassesOrObjects));
   }
 
   public Checks<C> addAnnotatedChecks(Iterable checkClassesOrObjects) {
diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/rules/AnnotationRuleParser.java b/sonar-plugin-api/src/main/java/org/sonar/api/rules/AnnotationRuleParser.java
index 88986262343..52596910143 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/rules/AnnotationRuleParser.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/rules/AnnotationRuleParser.java
@@ -44,8 +44,18 @@ import org.sonar.api.utils.log.Loggers;
 @ServerSide
 @ComputeEngineSide
 public final class AnnotationRuleParser {
-
   private static final Logger LOG = Loggers.get(AnnotationRuleParser.class);
+  private static final Map<Class<?>, PropertyType> TYPE_FOR_CLASS_MAP = new HashMap<>();
+  private static final Function<Class<?>, PropertyType> TYPE_FOR_CLASS = type -> TYPE_FOR_CLASS_MAP.getOrDefault(type, PropertyType.STRING);
+
+  static {
+    TYPE_FOR_CLASS_MAP.put(Integer.class, PropertyType.INTEGER);
+    TYPE_FOR_CLASS_MAP.put(int.class, PropertyType.INTEGER);
+    TYPE_FOR_CLASS_MAP.put(Float.class, PropertyType.FLOAT);
+    TYPE_FOR_CLASS_MAP.put(float.class, PropertyType.FLOAT);
+    TYPE_FOR_CLASS_MAP.put(Boolean.class, PropertyType.BOOLEAN);
+    TYPE_FOR_CLASS_MAP.put(boolean.class, PropertyType.BOOLEAN);
+  }
 
   public List<Rule> parse(String repositoryKey, Collection<Class> annotatedClasses) {
     List<Rule> rules = new ArrayList<>();
@@ -101,20 +111,6 @@ public final class AnnotationRuleParser {
     }
   }
 
-  private static final Map<Class<?>, PropertyType> TYPE_FOR_CLASS_MAP = new HashMap<>();
-
-  static {
-    TYPE_FOR_CLASS_MAP.put(Integer.class, PropertyType.INTEGER);
-    TYPE_FOR_CLASS_MAP.put(int.class, PropertyType.INTEGER);
-    TYPE_FOR_CLASS_MAP.put(Float.class, PropertyType.FLOAT);
-    TYPE_FOR_CLASS_MAP.put(float.class, PropertyType.FLOAT);
-    TYPE_FOR_CLASS_MAP.put(Boolean.class, PropertyType.BOOLEAN);
-    TYPE_FOR_CLASS_MAP.put(boolean.class, PropertyType.BOOLEAN);
-
-  }
-
-  private static final Function<Class<?>, PropertyType> TYPE_FOR_CLASS = type -> TYPE_FOR_CLASS_MAP.getOrDefault(type, PropertyType.STRING);
-
   static PropertyType guessType(Class<?> type) {
     return TYPE_FOR_CLASS.apply(type);
   }
diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/utils/text/CsvWriter.java b/sonar-plugin-api/src/main/java/org/sonar/api/utils/text/CsvWriter.java
index 919681d2422..97a4c677ced 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/utils/text/CsvWriter.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/utils/text/CsvWriter.java
@@ -28,10 +28,9 @@ import java.io.Writer;
  * @since 4.2
  */
 public class CsvWriter {
-
-  private final Writer writer;
   private static final String VALUE_SEPARATOR = ",";
   private static final String LINE_SEPARATOR = "\r\n";
+  private final Writer writer;
 
   private CsvWriter(Writer writer) {
     this.writer = writer;
diff --git a/sonar-plugin-api/src/test/java/org/sonar/api/rules/RulePriorityTest.java b/sonar-plugin-api/src/test/java/org/sonar/api/rules/RulePriorityTest.java
index 8d4e9451af6..602053cf8b4 100644
--- a/sonar-plugin-api/src/test/java/org/sonar/api/rules/RulePriorityTest.java
+++ b/sonar-plugin-api/src/test/java/org/sonar/api/rules/RulePriorityTest.java
@@ -28,12 +28,12 @@ public class RulePriorityTest {
 
   @Test
   public void testValueOfString() {
-    assertThat(RulePriority.INFO).isEqualTo(RulePriority.valueOfString("info"));
-    assertThat(RulePriority.MAJOR).isEqualTo(RulePriority.valueOfString("MAJOR"));
-    assertThat(RulePriority.MAJOR).isEqualTo(RulePriority.valueOfString("ERROR"));
-    assertThat(RulePriority.INFO).isEqualTo(RulePriority.valueOfString("WARNING"));
-    assertThat(RulePriority.MAJOR).isEqualTo(RulePriority.valueOfString("ErRor"));
-    assertThat(RulePriority.INFO).isEqualTo(RulePriority.valueOfString("WaRnInG"));
+    assertThat(RulePriority.valueOfString("info")).isEqualTo(RulePriority.INFO);
+    assertThat(RulePriority.valueOfString("MAJOR")).isEqualTo(RulePriority.MAJOR);
+    assertThat(RulePriority.valueOfString("ERROR")).isEqualTo(RulePriority.MAJOR);
+    assertThat(RulePriority.valueOfString("WARNING")).isEqualTo(RulePriority.INFO);
+    assertThat(RulePriority.valueOfString("ErRor")).isEqualTo(RulePriority.MAJOR);
+    assertThat(RulePriority.valueOfString("WaRnInG")).isEqualTo(RulePriority.INFO);
   }
 
   @Test(expected = IllegalArgumentException.class)
diff --git a/sonar-scanner-engine/src/main/java/org/sonar/scanner/scan/filesystem/CharsetValidation.java b/sonar-scanner-engine/src/main/java/org/sonar/scanner/scan/filesystem/CharsetValidation.java
index 87ac83ca0f8..53db0643f1e 100644
--- a/sonar-scanner-engine/src/main/java/org/sonar/scanner/scan/filesystem/CharsetValidation.java
+++ b/sonar-scanner-engine/src/main/java/org/sonar/scanner/scan/filesystem/CharsetValidation.java
@@ -93,8 +93,8 @@ public class CharsetValidation {
       }
     }
 
-    double beAsciiPerc = beAscii * 2.0 / (double) buffer.length;
-    double leAsciiPerc = leAscii * 2.0 / (double) buffer.length;
+    double beAsciiPerc = beAscii * 2.0D / buffer.length;
+    double leAsciiPerc = leAscii * 2.0D / buffer.length;
 
     if (leLines == 0) {
       // could be BE