SONAR-4699 Period by date should return null when no snapshot found

sonar-batch/src/main/java/org/sonar/batch/components/PastSnapshotFinderByDate.java

@@ -26,6 +26,8 @@ import org.sonar.api.database.model.Snapshot;
 import org.sonar.api.resources.Qualifiers;
 import org.sonar.api.utils.DateUtils;
 
+import javax.annotation.Nullable;
+
 import java.text.SimpleDateFormat;
 import java.util.Date;
 import java.util.List;
@@ -47,7 +49,7 @@ public class PastSnapshotFinderByDate implements BatchExtension {
     return new PastSnapshot(CoreProperties.TIMEMACHINE_MODE_DATE, date, snapshot).setModeParameter(format.format(date));
   }
 
-
+  @Nullable
   private Snapshot findSnapshot(Snapshot projectSnapshot, Date date) {
     String hql = "from " + Snapshot.class.getSimpleName() + " where createdAt>=:date AND resourceId=:resourceId AND status=:status AND qualifier<>:lib order by createdAt asc";
     List<Snapshot> snapshots = session.createQuery(hql)

sonar-batch/src/main/java/org/sonar/batch/components/PastSnapshotFinderByDays.java

@@ -26,6 +26,8 @@ import org.sonar.api.database.DatabaseSession;
 import org.sonar.api.database.model.Snapshot;
 import org.sonar.api.resources.Qualifiers;
 
+import javax.annotation.Nullable;
+
 import java.util.Date;
 import java.util.List;
 
@@ -51,11 +53,13 @@ public class PastSnapshotFinderByDays implements BatchExtension {
     return new PastSnapshot(CoreProperties.TIMEMACHINE_MODE_DAYS, targetDate, snapshot).setModeParameter(String.valueOf(days));
   }
 
+  @Nullable
   static Snapshot getNearestToTarget(List<Snapshot> snapshots, Date currentDate, int distanceInDays) {
     Date targetDate = DateUtils.addDays(currentDate, -distanceInDays);
     return getNearestToTarget(snapshots, targetDate);
   }
 
+  @Nullable
   static Snapshot getNearestToTarget(List<Snapshot> snapshots, Date targetDate) {
     long bestDistance = Long.MAX_VALUE;
     Snapshot nearest = null;

sonar-batch/src/main/java/org/sonar/batch/components/TimeMachineConfiguration.java

@@ -31,6 +31,7 @@ import org.sonar.api.resources.Project;
 import org.sonar.api.resources.Qualifiers;
 
 import javax.persistence.Query;
+
 import java.util.Date;
 import java.util.List;
 
@@ -68,7 +69,8 @@ public class TimeMachineConfiguration implements BatchExtension {
     if (projectSnapshot != null) {
       for (int index = 1; index <= NUMBER_OF_VARIATION_SNAPSHOTS; index++) {
         PastSnapshot pastSnapshot = pastSnapshotFinder.find(projectSnapshot, rootQualifier, settings, index);
-        if (pastSnapshot != null) {
+        // SONAR-4700 Add a past snapshot only if it exists
+        if (pastSnapshot != null && pastSnapshot.getProjectSnapshot() != null) {
           log(pastSnapshot);
           projectPastSnapshots.add(pastSnapshot);
         }

sonar-batch/src/main/java/org/sonar/batch/components/package-info.java

@@ -0,0 +1,23 @@
+/*
+ * SonarQube, open source software quality management tool.
+ * Copyright (C) 2008-2013 SonarSource
+ * mailto:contact AT sonarsource DOT com
+ *
+ * SonarQube 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.
+ *
+ * SonarQube 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.batch.components;
+
+import javax.annotation.ParametersAreNonnullByDefault;