Simplify lambda expressions (#10198)

* Simplify lambda expressions

And remove unneeded 'return' keyword.

* Format

32 files changed, 128 insertions, 184 deletions

diff --git a/server/src/main/java/com/vaadin/data/Validator.java b/server/src/main/java/com/vaadin/data/Validator.java
index 4f8f4dc8ca..be6b89188a 100644
--- a/server/src/main/java/com/vaadin/data/Validator.java
+++ b/server/src/main/java/com/vaadin/data/Validator.java
@@ -186,10 +186,9 @@ public interface Validator<T>
             try {
                 if (guard.test(value)) {
                     return ValidationResult.ok();
-                } else {
-                    return ValidationResult.create(
-                            errorMessageProvider.apply(context), errorLevel);
                 }
+                return ValidationResult.create(
+                        errorMessageProvider.apply(context), errorLevel);
             } catch (Exception e) {
                 return ValidationResult.create(
                         errorMessageProvider.apply(context), errorLevel);
diff --git a/server/src/main/java/com/vaadin/data/converter/StringToBigIntegerConverter.java b/server/src/main/java/com/vaadin/data/converter/StringToBigIntegerConverter.java
index 40683abb22..840f6ae8c0 100644
--- a/server/src/main/java/com/vaadin/data/converter/StringToBigIntegerConverter.java
+++ b/server/src/main/java/com/vaadin/data/converter/StringToBigIntegerConverter.java
@@ -84,13 +84,12 @@ public class StringToBigIntegerConverter
                 .map(number -> {
                     if (number == null) {
                         return null;
-                    } else {
-                        // Empty value will be a BigInteger
-                        if (number instanceof BigInteger) {
-                            return (BigInteger) number;
-                        }
-                        return ((BigDecimal) number).toBigInteger();
                     }
+                    // Empty value will be a BigInteger
+                    if (number instanceof BigInteger) {
+                        return (BigInteger) number;
+                    }
+                    return ((BigDecimal) number).toBigInteger();
                 });
     }
 
diff --git a/server/src/main/java/com/vaadin/data/converter/StringToDoubleConverter.java b/server/src/main/java/com/vaadin/data/converter/StringToDoubleConverter.java
index a2eb45dce1..627775fbba 100644
--- a/server/src/main/java/com/vaadin/data/converter/StringToDoubleConverter.java
+++ b/server/src/main/java/com/vaadin/data/converter/StringToDoubleConverter.java
@@ -72,9 +72,8 @@ public class StringToDoubleConverter
         return n.map(number -> {
             if (number == null) {
                 return null;
-            } else {
-                return number.doubleValue();
             }
+            return number.doubleValue();
         });
     }
 
diff --git a/server/src/main/java/com/vaadin/data/converter/StringToFloatConverter.java b/server/src/main/java/com/vaadin/data/converter/StringToFloatConverter.java
index 6598c0f6fd..37e159f844 100644
--- a/server/src/main/java/com/vaadin/data/converter/StringToFloatConverter.java
+++ b/server/src/main/java/com/vaadin/data/converter/StringToFloatConverter.java
@@ -70,9 +70,8 @@ public class StringToFloatConverter
         return n.map(number -> {
             if (number == null) {
                 return null;
-            } else {
-                return number.floatValue();
             }
+            return number.floatValue();
         });
     }
 
diff --git a/server/src/main/java/com/vaadin/data/converter/StringToIntegerConverter.java b/server/src/main/java/com/vaadin/data/converter/StringToIntegerConverter.java
index 71709e9927..88f2c29126 100644
--- a/server/src/main/java/com/vaadin/data/converter/StringToIntegerConverter.java
+++ b/server/src/main/java/com/vaadin/data/converter/StringToIntegerConverter.java
@@ -85,18 +85,16 @@ public class StringToIntegerConverter
         return n.flatMap(number -> {
             if (number == null) {
                 return Result.ok(null);
-            } else {
-                int intValue = number.intValue();
-                if (intValue == number.longValue()) {
-                    // If the value of n is outside the range of long, the
-                    // return value of longValue() is either Long.MIN_VALUE or
-                    // Long.MAX_VALUE. The/ above comparison promotes int to
-                    // long and thus does not need to consider wrap-around.
-                    return Result.ok(intValue);
-                } else {
-                    return Result.error(getErrorMessage());
-                }
             }
+            int intValue = number.intValue();
+            if (intValue == number.longValue()) {
+                // If the value of n is outside the range of long, the
+                // return value of longValue() is either Long.MIN_VALUE or
+                // Long.MAX_VALUE. The/ above comparison promotes int to
+                // long and thus does not need to consider wrap-around.
+                return Result.ok(intValue);
+            }
+            return Result.error(getErrorMessage());
         });
     }
 
diff --git a/server/src/main/java/com/vaadin/data/converter/StringToLongConverter.java b/server/src/main/java/com/vaadin/data/converter/StringToLongConverter.java
index 00364dbbc9..4e65296316 100644
--- a/server/src/main/java/com/vaadin/data/converter/StringToLongConverter.java
+++ b/server/src/main/java/com/vaadin/data/converter/StringToLongConverter.java
@@ -85,9 +85,8 @@ public class StringToLongConverter
         return n.map(number -> {
             if (number == null) {
                 return null;
-            } else {
-                return number.longValue();
             }
+            return number.longValue();
         });
     }
 
diff --git a/server/src/main/java/com/vaadin/data/provider/InMemoryDataProviderHelpers.java b/server/src/main/java/com/vaadin/data/provider/InMemoryDataProviderHelpers.java
index 556404911c..785079bb0d 100644
--- a/server/src/main/java/com/vaadin/data/provider/InMemoryDataProviderHelpers.java
+++ b/server/src/main/java/com/vaadin/data/provider/InMemoryDataProviderHelpers.java
@@ -46,9 +46,8 @@ public class InMemoryDataProviderHelpers {
         UI currentUi = UI.getCurrent();
         if (currentUi != null) {
             return currentUi.getLocale();
-        } else {
-            return Locale.getDefault();
         }
+        return Locale.getDefault();
     };
 
     /**
diff --git a/server/src/main/java/com/vaadin/navigator/Navigator.java b/server/src/main/java/com/vaadin/navigator/Navigator.java
index 81e141319d..22b22678b0 100644
--- a/server/src/main/java/com/vaadin/navigator/Navigator.java
+++ b/server/src/main/java/com/vaadin/navigator/Navigator.java
@@ -120,10 +120,8 @@ public class Navigator implements Serializable {
                 popStateListenerRegistration = null;
             }
             if (navigator != null) {
-                popStateListenerRegistration = ui.getPage()
-                        .addPopStateListener(e -> {
-                            navigator.navigateTo(getState());
-                        });
+                popStateListenerRegistration = ui.getPage().addPopStateListener(
+                        e -> navigator.navigateTo(getState()));
             }
         }
 
@@ -700,10 +698,8 @@ public class Navigator implements Serializable {
      *            parameters passed in the navigation state to the view
      */
     protected void navigateTo(View view, String viewName, String parameters) {
-        runAfterLeaveConfirmation(() -> {
-            performNavigateTo(view, viewName, parameters);
-        });
-
+        runAfterLeaveConfirmation(
+                () -> performNavigateTo(view, viewName, parameters));
     }
 
     /**
diff --git a/server/src/main/java/com/vaadin/server/communication/FileUploadHandler.java b/server/src/main/java/com/vaadin/server/communication/FileUploadHandler.java
index b54c9622d6..c0221af38e 100644
--- a/server/src/main/java/com/vaadin/server/communication/FileUploadHandler.java
+++ b/server/src/main/java/com/vaadin/server/communication/FileUploadHandler.java
@@ -694,9 +694,7 @@ public class FileUploadHandler implements RequestHandler {
 
     private void cleanStreamVariable(VaadinSession session, final UI ui,
             final ClientConnector owner, final String variableName) {
-        session.accessSynchronously(() -> {
-            ui.getConnectorTracker().cleanStreamVariable(owner.getConnectorId(),
-                    variableName);
-        });
+        session.accessSynchronously(() -> ui.getConnectorTracker()
+                .cleanStreamVariable(owner.getConnectorId(), variableName));
     }
 }
diff --git a/server/src/main/java/com/vaadin/server/communication/PushRequestHandler.java b/server/src/main/java/com/vaadin/server/communication/PushRequestHandler.java
index 9e15d5c0fe..04fcbd0c80 100644
--- a/server/src/main/java/com/vaadin/server/communication/PushRequestHandler.java
+++ b/server/src/main/java/com/vaadin/server/communication/PushRequestHandler.java
@@ -36,7 +36,6 @@ import org.atmosphere.interceptor.HeartbeatInterceptor;
 import org.atmosphere.util.VoidAnnotationProcessor;
 
 import com.vaadin.server.RequestHandler;
-import com.vaadin.server.ServiceDestroyEvent;
 import com.vaadin.server.ServiceException;
 import com.vaadin.server.ServletPortletHelper;
 import com.vaadin.server.SessionExpiredHandler;
@@ -66,9 +65,7 @@ public class PushRequestHandler
     public PushRequestHandler(VaadinServletService service)
             throws ServiceException {
 
-        service.addServiceDestroyListener((ServiceDestroyEvent event) -> {
-            destroy();
-        });
+        service.addServiceDestroyListener(e -> destroy());
 
         final ServletConfig vaadinServletConfig = service.getServlet()
                 .getServletConfig();
diff --git a/server/src/main/java/com/vaadin/ui/AbstractComponent.java b/server/src/main/java/com/vaadin/ui/AbstractComponent.java
index 2c9c40e668..88b42d5757 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractComponent.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractComponent.java
@@ -1388,10 +1388,10 @@ public abstract class AbstractComponent extends AbstractClientConnector
         // called if there are no listeners on the server-side. A client-side
         // connector can override this and use a different RPC channel.
         if (getRpcManager(ContextClickRpc.class.getName()) == null) {
-            registerRpc((ContextClickRpc) (MouseEventDetails details) -> {
-                fireEvent(
-                        new ContextClickEvent(AbstractComponent.this, details));
-            });
+            registerRpc(
+                    (ContextClickRpc) (MouseEventDetails details) -> fireEvent(
+                            new ContextClickEvent(AbstractComponent.this,
+                                    details)));
         }
 
         return addListener(EventId.CONTEXT_CLICK, ContextClickEvent.class,
diff --git a/server/src/main/java/com/vaadin/ui/ComboBox.java b/server/src/main/java/com/vaadin/ui/ComboBox.java
index 6e03ed35e9..c6765dde1a 100644
--- a/server/src/main/java/com/vaadin/ui/ComboBox.java
+++ b/server/src/main/java/com/vaadin/ui/ComboBox.java
@@ -678,10 +678,9 @@ public class ComboBox<T> extends AbstractSingleSelect<T>
     @Override
     public Registration addValueChangeListener(
             HasValue.ValueChangeListener<T> listener) {
-        return addSelectionListener(event -> {
-            listener.valueChange(new ValueChangeEvent<>(event.getComponent(),
-                    this, event.getOldValue(), event.isUserOriginated()));
-        });
+        return addSelectionListener(event -> listener
+                .valueChange(new ValueChangeEvent<>(event.getComponent(), this,
+                        event.getOldValue(), event.isUserOriginated())));
     }
 
     @Override
diff --git a/server/src/main/java/com/vaadin/ui/CssLayout.java b/server/src/main/java/com/vaadin/ui/CssLayout.java
index a407859d08..4540a9feb9 100644
--- a/server/src/main/java/com/vaadin/ui/CssLayout.java
+++ b/server/src/main/java/com/vaadin/ui/CssLayout.java
@@ -76,10 +76,10 @@ import com.vaadin.ui.declarative.DesignContext;
 public class CssLayout extends AbstractLayout implements LayoutClickNotifier {
 
     private CssLayoutServerRpc rpc = (MouseEventDetails mouseDetails,
-            Connector clickedConnector) -> {
-        fireEvent(LayoutClickEvent.createEvent(CssLayout.this, mouseDetails,
-                clickedConnector));
-    };
+            Connector clickedConnector) -> fireEvent(
+                    LayoutClickEvent.createEvent(CssLayout.this, mouseDetails,
+                            clickedConnector));
+
     /**
      * Custom layout slots containing the components.
      */
diff --git a/server/src/main/java/com/vaadin/ui/Grid.java b/server/src/main/java/com/vaadin/ui/Grid.java
index 2b4723eaaa..de8f66ee58 100644
--- a/server/src/main/java/com/vaadin/ui/Grid.java
+++ b/server/src/main/java/com/vaadin/ui/Grid.java
@@ -403,12 +403,12 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
      *
      * <p>
      * Usage:
-     * 
+     *
      * <pre>
      * grid.addContextClickListener(event -&gt; Notification.show(
      *         ((GridContextClickEvent&lt;Person&gt;) event).getItem() + " Clicked"));
      * </pre>
-     * 
+     *
      * @param <T>
      *            the grid bean type
      */
@@ -836,9 +836,8 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
             String id = getId();
             if (id == null) {
                 return Stream.empty();
-            } else {
-                return Stream.of(new QuerySortOrder(id, direction));
             }
+            return Stream.of(new QuerySortOrder(id, direction));
         };
 
         private SerializableComparator<T> comparator;
@@ -3018,7 +3017,7 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
      * Note that all header, body and footer rows get the same height if
      * explicitly set. In automatic mode, each section is calculated separately
      * based on an empty row of that type.
-     * 
+     *
      * @see #setBodyRowHeight(double)
      * @see #setHeaderRowHeight(double)
      * @see #setFooterRowHeight(double)
@@ -3036,7 +3035,7 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
      * Sets the height of a body row. If -1 (default), the row height is
      * calculated based on the theme for an empty row before the Grid is
      * displayed.
-     * 
+     *
      * @param rowHeight
      *            The height of a row in pixels or -1 for automatic calculation
      * @since 8.2
@@ -3293,10 +3292,10 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
 
     /**
      * Sets the visibility of the Header in this Grid.
-     * 
+     *
      * @param headerVisible
      *            {@code true} if visible; {@code false} if not
-     * 
+     *
      * @since 8.1.1
      */
     public void setHeaderVisible(boolean headerVisible) {
@@ -3305,9 +3304,9 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
 
     /**
      * Gets the visibility of the Header in this Grid.
-     * 
+     *
      * @return {@code true} if visible; {@code false} if not
-     * 
+     *
      * @since 8.1.1
      */
     public boolean isHeaderVisible() {
@@ -3466,10 +3465,10 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
 
     /**
      * Sets the visibility of the Footer in this Grid.
-     * 
+     *
      * @param footerVisible
      *            {@code true} if visible; {@code false} if not
-     * 
+     *
      * @since 8.1.1
      */
     public void setFooterVisible(boolean footerVisible) {
@@ -3478,9 +3477,9 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
 
     /**
      * Gets the visibility of the Footer in this Grid.
-     * 
+     *
      * @return {@code true} if visible; {@code false} if not
-     * 
+     *
      * @since 8.1.1
      */
     public boolean isFooterVisible() {
@@ -3651,7 +3650,6 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
                         "setColumnOrder should not be called "
                                 + "with columns that are not in the grid.");
             }
-
         });
 
         List<String> stateColumnOrder = getState().columnOrder;
@@ -4572,14 +4570,13 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
      * @return the comparator based on column sorting information.
      */
     protected SerializableComparator<T> createSortingComparator() {
+        /*
+         * thenComparing is defined to return a serializable comparator as long
+         * as both original comparators are also serializable
+         */
         BinaryOperator<SerializableComparator<T>> operator = (comparator1,
-                comparator2) -> {
-            /*
-             * thenComparing is defined to return a serializable comparator as
-             * long as both original comparators are also serializable
-             */
-            return comparator1.thenComparing(comparator2)::compare;
-        };
+                comparator2) ->
+        comparator1.thenComparing(comparator2)::compare;
         return sortOrder.stream().map(
                 order -> order.getSorted().getComparator(order.getDirection()))
                 .reduce((x, y) -> 0, operator);
diff --git a/server/src/main/java/com/vaadin/ui/GridLayout.java b/server/src/main/java/com/vaadin/ui/GridLayout.java
index 27e1835b57..ebffa061e8 100644
--- a/server/src/main/java/com/vaadin/ui/GridLayout.java
+++ b/server/src/main/java/com/vaadin/ui/GridLayout.java
@@ -77,10 +77,10 @@ public class GridLayout extends AbstractLayout
         Layout.MarginHandler, LayoutClickNotifier {
 
     private GridLayoutServerRpc rpc = (MouseEventDetails mouseDetails,
-            Connector clickedConnector) -> {
-        fireEvent(LayoutClickEvent.createEvent(GridLayout.this, mouseDetails,
-                clickedConnector));
-    };
+            Connector clickedConnector) -> fireEvent(
+                    LayoutClickEvent.createEvent(GridLayout.this, mouseDetails,
+                            clickedConnector));
+
     /**
      * Cursor X position: this is where the next component with unspecified x,y
      * is inserted
diff --git a/server/src/main/java/com/vaadin/ui/Image.java b/server/src/main/java/com/vaadin/ui/Image.java
index 4f3650a9f2..4b1d7dae00 100644
--- a/server/src/main/java/com/vaadin/ui/Image.java
+++ b/server/src/main/java/com/vaadin/ui/Image.java
@@ -33,9 +33,9 @@ import com.vaadin.shared.ui.image.ImageState;
 @SuppressWarnings("serial")
 public class Image extends AbstractEmbedded {
 
-    protected ImageServerRpc rpc = (MouseEventDetails mouseDetails) -> {
-        fireEvent(new ClickEvent(Image.this, mouseDetails));
-    };
+    protected ImageServerRpc rpc = (
+            MouseEventDetails mouseDetails) -> fireEvent(
+                    new ClickEvent(Image.this, mouseDetails));
 
     /**
      * Creates a new empty Image.
diff --git a/server/src/main/java/com/vaadin/ui/Notification.java b/server/src/main/java/com/vaadin/ui/Notification.java
index 83c145ec70..0c3158bf97 100644
--- a/server/src/main/java/com/vaadin/ui/Notification.java
+++ b/server/src/main/java/com/vaadin/ui/Notification.java
@@ -74,9 +74,8 @@ public class Notification extends AbstractExtension implements Serializable {
      *
      * @since 8.2
      */
-    protected NotificationServerRpc rpc = () -> {
-        fireEvent(new CloseEvent(Notification.this));
-    };
+    protected NotificationServerRpc rpc = () -> fireEvent(
+            new CloseEvent(Notification.this));
 
     public enum Type {
         HUMANIZED_MESSAGE("humanized"), WARNING_MESSAGE(
diff --git a/server/src/main/java/com/vaadin/ui/Panel.java b/server/src/main/java/com/vaadin/ui/Panel.java
index def5893946..6b06b02fe4 100644
--- a/server/src/main/java/com/vaadin/ui/Panel.java
+++ b/server/src/main/java/com/vaadin/ui/Panel.java
@@ -53,9 +53,8 @@ public class Panel extends AbstractSingleComponentContainer
      */
     protected ActionManager actionManager;
 
-    private PanelServerRpc rpc = (MouseEventDetails mouseDetails) -> {
-        fireEvent(new ClickEvent(Panel.this, mouseDetails));
-    };
+    private PanelServerRpc rpc = (MouseEventDetails mouseDetails) -> fireEvent(
+            new ClickEvent(Panel.this, mouseDetails));
 
     /**
      * Creates a new empty panel.
diff --git a/server/src/main/java/com/vaadin/ui/components/grid/GridDragSource.java b/server/src/main/java/com/vaadin/ui/components/grid/GridDragSource.java
index cf5051abb4..c84cc9534d 100644
--- a/server/src/main/java/com/vaadin/ui/components/grid/GridDragSource.java
+++ b/server/src/main/java/com/vaadin/ui/components/grid/GridDragSource.java
@@ -149,9 +149,8 @@ public class GridDragSource<T> extends DragSourceExtension<Grid<T>> {
     private void generateDragData(T item, JsonObject jsonObject) {
         JsonObject generatedValues = Json.createObject();
 
-        generatorFunctions.forEach((type, generator) -> {
-            generatedValues.put(type, generator.apply(item));
-        });
+        generatorFunctions.forEach((type, generator) -> generatedValues
+                .put(type, generator.apply(item)));
 
         jsonObject.put(GridDragSourceState.JSONKEY_DRAG_DATA, generatedValues);
     }
diff --git a/server/src/main/java/com/vaadin/ui/declarative/Design.java b/server/src/main/java/com/vaadin/ui/declarative/Design.java
index 8d723ef47e..61d35297d0 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/Design.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/Design.java
@@ -490,9 +490,8 @@ public class Design implements Serializable {
             // create listener for component creations that binds the created
             // components to the componentRoot instance fields
             ComponentCreationListener creationListener = (
-                    ComponentCreatedEvent event) -> {
-                binder.bindField(event.getComponent(), event.getLocalId());
-            };
+                    ComponentCreatedEvent event) -> binder.bindField(
+                            event.getComponent(), event.getLocalId());
             designContext.addComponentCreationListener(creationListener);
 
             // create subtree
diff --git a/server/src/main/java/com/vaadin/ui/dnd/DropTargetExtension.java b/server/src/main/java/com/vaadin/ui/dnd/DropTargetExtension.java
index 4cff2545e8..76c7195f60 100644
--- a/server/src/main/java/com/vaadin/ui/dnd/DropTargetExtension.java
+++ b/server/src/main/java/com/vaadin/ui/dnd/DropTargetExtension.java
@@ -24,10 +24,10 @@ import java.util.Objects;
 import com.vaadin.server.AbstractExtension;
 import com.vaadin.shared.MouseEventDetails;
 import com.vaadin.shared.Registration;
-import com.vaadin.shared.ui.dnd.criteria.ComparisonOperator;
 import com.vaadin.shared.ui.dnd.DropEffect;
 import com.vaadin.shared.ui.dnd.DropTargetRpc;
 import com.vaadin.shared.ui.dnd.DropTargetState;
+import com.vaadin.shared.ui.dnd.criteria.ComparisonOperator;
 import com.vaadin.shared.ui.dnd.criteria.Criterion;
 import com.vaadin.ui.AbstractComponent;
 import com.vaadin.ui.dnd.event.DropEvent;
@@ -73,11 +73,10 @@ public class DropTargetExtension<T extends AbstractComponent>
      */
     protected void registerDropTargetRpc() {
         registerRpc(
-                (DropTargetRpc) (types, data, dropEffect, mouseEventDetails) -> {
-                    onDrop(types, data,
-                            DropEffect.valueOf(dropEffect.toUpperCase()),
-                            mouseEventDetails);
-                });
+                (DropTargetRpc) (types, data, dropEffect, mouseEventDetails) ->
+                onDrop(types, data,
+                        DropEffect.valueOf(dropEffect.toUpperCase()),
+                        mouseEventDetails));
     }
 
     /**
diff --git a/server/src/test/java/com/vaadin/data/BinderConverterValidatorTest.java b/server/src/test/java/com/vaadin/data/BinderConverterValidatorTest.java
index 734aa5b194..a451e2b9be 100644
--- a/server/src/test/java/com/vaadin/data/BinderConverterValidatorTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderConverterValidatorTest.java
@@ -127,9 +127,8 @@ public class BinderConverterValidatorTest
         Validator<Number> positiveNumberValidator = (value, context) -> {
             if (value.doubleValue() >= 0) {
                 return ValidationResult.ok();
-            } else {
-                return ValidationResult.error(NEGATIVE_ERROR_MESSAGE);
             }
+            return ValidationResult.error(NEGATIVE_ERROR_MESSAGE);
         };
         binder.forField(salaryField)
                 .withConverter(Double::valueOf, String::valueOf)
@@ -227,7 +226,8 @@ public class BinderConverterValidatorTest
                 .withConverter(presentation -> {
                     if (presentation.equals("OK")) {
                         return "1";
-                    } else if (presentation.equals("NOTOK")) {
+                    }
+                    if (presentation.equals("NOTOK")) {
                         return "2";
                     }
                     throw new IllegalArgumentException(
@@ -235,12 +235,12 @@ public class BinderConverterValidatorTest
                 }, model -> {
                     if (model.equals("1")) {
                         return "OK";
-                    } else if (model.equals("2")) {
+                    }
+                    if (model.equals("2")) {
                         return "NOTOK";
-                    } else {
-                        throw new IllegalArgumentException(
-                                "Value in model must be 1 or 2");
                     }
+                    throw new IllegalArgumentException(
+                            "Value in model must be 1 or 2");
                 });
         binding.bind(StatusBean::getStatus, StatusBean::setStatus);
         binder.setBean(bean);
@@ -535,12 +535,9 @@ public class BinderConverterValidatorTest
         binder.forField(nameField).withConverter(fieldValue -> {
             if ("null".equals(fieldValue)) {
                 return null;
-            } else {
-                return fieldValue;
             }
-        }, model -> {
-            return model;
-        }).bind(Person::getFirstName, Person::setFirstName);
+            return fieldValue;
+        }, model -> model).bind(Person::getFirstName, Person::setFirstName);
 
         Person person = new Person();
         person.setFirstName("foo");
diff --git a/server/src/test/java/com/vaadin/data/BinderTest.java b/server/src/test/java/com/vaadin/data/BinderTest.java
index 032ce99580..7b45ee95e0 100644
--- a/server/src/test/java/com/vaadin/data/BinderTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderTest.java
@@ -394,8 +394,9 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
         String customNullPointerRepresentation = "foo";
         Binder<Person> binder = new Binder<>(Person.class);
         binder.forField(nameField)
-                .withConverter(value -> value, value -> value == null
-                        ? customNullPointerRepresentation : value)
+                .withConverter(value -> value,
+                        value -> value == null ? customNullPointerRepresentation
+                                : value)
                 .bind("firstName");
 
         Person person = new Person();
@@ -892,9 +893,8 @@ public class BinderTest extends BinderTestBase<Binder<Person>, Person> {
                 .withConverter(new StringToIntegerConverter(ageError))
                 .bind(Person::getAge, Person::setAge);
 
-        binder.setValidationStatusHandler(status -> {
-            status.notifyBindingValidationStatusHandlers();
-        });
+        binder.setValidationStatusHandler(
+                status -> status.notifyBindingValidationStatusHandlers());
 
         String initialName = item.getFirstName();
         int initialAge = item.getAge();
diff --git a/server/src/test/java/com/vaadin/data/BinderValidationStatusTest.java b/server/src/test/java/com/vaadin/data/BinderValidationStatusTest.java
index dcf568cafc..7df1537bd0 100644
--- a/server/src/test/java/com/vaadin/data/BinderValidationStatusTest.java
+++ b/server/src/test/java/com/vaadin/data/BinderValidationStatusTest.java
@@ -215,17 +215,16 @@ public class BinderValidationStatusTest
     public void binderWithStatusHandler_fieldValidationNoBeanValidation_handlerGetsStatusUpdates() {
         AtomicReference<BinderValidationStatus<?>> statusCapture = new AtomicReference<>();
         binder.forField(nameField).withValidator(notEmpty)
-                .withValidationStatusHandler(evt -> {
-                    fail("Using a custom status change handler so no change should end up here");
-                }).bind(Person::getFirstName, Person::setFirstName);
+                .withValidationStatusHandler(evt -> fail(
+                        "Using a custom status change handler so no change should end up here"))
+                .bind(Person::getFirstName, Person::setFirstName);
         binder.forField(ageField).withConverter(stringToInteger)
-                .withValidator(notNegative).withValidationStatusHandler(evt -> {
-                    fail("Using a custom status change handler so no change should end up here");
-                }).bind(Person::getAge, Person::setAge);
+                .withValidator(notNegative)
+                .withValidationStatusHandler(evt -> fail(
+                        "Using a custom status change handler so no change should end up here"))
+                .bind(Person::getAge, Person::setAge);
 
-        binder.setValidationStatusHandler(r -> {
-            statusCapture.set(r);
-        });
+        binder.setValidationStatusHandler(r -> statusCapture.set(r));
         binder.setBean(item);
         assertNull(nameField.getComponentError());
 
@@ -303,20 +302,19 @@ public class BinderValidationStatusTest
     public void binderWithStatusHandler_fieldAndBeanLevelValidation_handlerGetsStatusUpdates() {
         AtomicReference<BinderValidationStatus<?>> statusCapture = new AtomicReference<>();
         binder.forField(nameField).withValidator(notEmpty)
-                .withValidationStatusHandler(evt -> {
-                    fail("Using a custom status change handler so no change should end up here");
-                }).bind(Person::getFirstName, Person::setFirstName);
+                .withValidationStatusHandler(evt -> fail(
+                        "Using a custom status change handler so no change should end up here"))
+                .bind(Person::getFirstName, Person::setFirstName);
         binder.forField(ageField).withConverter(stringToInteger)
-                .withValidator(notNegative).withValidationStatusHandler(evt -> {
-                    fail("Using a custom status change handler so no change should end up here");
-                }).bind(Person::getAge, Person::setAge);
+                .withValidator(notNegative)
+                .withValidationStatusHandler(evt -> fail(
+                        "Using a custom status change handler so no change should end up here"))
+                .bind(Person::getAge, Person::setAge);
         binder.withValidator(
                 bean -> !bean.getFirstName().isEmpty() && bean.getAge() > 0,
                 "Need first name and age");
 
-        binder.setValidationStatusHandler(r -> {
-            statusCapture.set(r);
-        });
+        binder.setValidationStatusHandler(r -> statusCapture.set(r));
         binder.setBean(item);
         assertNull(nameField.getComponentError());
 
@@ -489,13 +487,9 @@ public class BinderValidationStatusTest
         BindingBuilder<Person, String> binding = binder.forField(nameField);
         binding.bind(Person::getFirstName, Person::setFirstName);
 
-        binder.setValidationStatusHandler(results -> {
-            fail();
-        });
+        binder.setValidationStatusHandler(results -> fail());
 
-        binder.setValidationStatusHandler(results -> {
-            capture.set(results);
-        });
+        binder.setValidationStatusHandler(results -> capture.set(results));
 
         nameField.setValue("foo");
         binder.validate();
diff --git a/server/src/test/java/com/vaadin/data/ValidatorTest.java b/server/src/test/java/com/vaadin/data/ValidatorTest.java
index 7d29b6941e..b2c21581f5 100644
--- a/server/src/test/java/com/vaadin/data/ValidatorTest.java
+++ b/server/src/test/java/com/vaadin/data/ValidatorTest.java
@@ -61,7 +61,8 @@ public class ValidatorTest extends ValidatorTestBase {
 
                     if (locale.getLanguage().equals("fi")) {
                         return finnishError;
-                    } else if (locale.getLanguage().equals("en")) {
+                    }
+                    if (locale.getLanguage().equals("en")) {
                         return englishError;
                     }
                     return notTranslatableError;
diff --git a/server/src/test/java/com/vaadin/server/VaadinServiceTest.java b/server/src/test/java/com/vaadin/server/VaadinServiceTest.java
index 6219be0a29..6e40fdf0ce 100644
--- a/server/src/test/java/com/vaadin/server/VaadinServiceTest.java
+++ b/server/src/test/java/com/vaadin/server/VaadinServiceTest.java
@@ -158,9 +158,8 @@ public class VaadinServiceTest {
 
         MockVaadinSession session = new MockVaadinSession(service);
         session.lock();
-        service.accessSession(session, () -> {
-            CurrentInstance.set(String.class, "Set in task");
-        });
+        service.accessSession(session,
+                () -> CurrentInstance.set(String.class, "Set in task"));
 
         CurrentInstance.set(String.class, "Original value");
         service.runPendingAccessTasks(session);
diff --git a/server/src/test/java/com/vaadin/tests/data/converter/ConverterTest.java b/server/src/test/java/com/vaadin/tests/data/converter/ConverterTest.java
index 3c31fddd7e..81304885c3 100644
--- a/server/src/test/java/com/vaadin/tests/data/converter/ConverterTest.java
+++ b/server/src/test/java/com/vaadin/tests/data/converter/ConverterTest.java
@@ -14,9 +14,8 @@ public class ConverterTest {
     SerializableFunction<String, Result<String>> toModel = presentation -> {
         if (presentation.startsWith("presentation-")) {
             return Result.ok(presentation.substring("presentation-".length()));
-        } else {
-            return Result.error("invalid prefix: " + presentation);
         }
+        return Result.error("invalid prefix: " + presentation);
     };
 
     SerializableFunction<String, String> toPresentation = model -> "presentation-"
diff --git a/server/src/test/java/com/vaadin/tests/design/designroot/ExtendedDesignWithEmptyAnnotation.java b/server/src/test/java/com/vaadin/tests/design/designroot/ExtendedDesignWithEmptyAnnotation.java
index f3a44a7bf2..5a21e7e793 100644
--- a/server/src/test/java/com/vaadin/tests/design/designroot/ExtendedDesignWithEmptyAnnotation.java
+++ b/server/src/test/java/com/vaadin/tests/design/designroot/ExtendedDesignWithEmptyAnnotation.java
@@ -15,7 +15,6 @@
  */
 package com.vaadin.tests.design.designroot;
 
-import com.vaadin.ui.Button.ClickEvent;
 import com.vaadin.ui.Notification;
 import com.vaadin.ui.TextField;
 
@@ -29,12 +28,8 @@ public class ExtendedDesignWithEmptyAnnotation
         customField.setPlaceholder("Something");
         addComponent(customField);
 
-        ok.addClickListener((ClickEvent event) -> {
-            Notification.show("OK");
-        });
+        ok.addClickListener(e -> Notification.show("OK"));
 
-        CaNCEL.addClickListener((ClickEvent event) -> {
-            Notification.show("cancel");
-        });
+        CaNCEL.addClickListener(e -> Notification.show("cancel"));
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/button/ButtonClickTest.java b/server/src/test/java/com/vaadin/tests/server/component/button/ButtonClickTest.java
index 2adbfe2df8..45844bee25 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/button/ButtonClickTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/button/ButtonClickTest.java
@@ -10,7 +10,6 @@ import org.junit.Test;
 
 import com.vaadin.server.VaadinRequest;
 import com.vaadin.ui.Button;
-import com.vaadin.ui.Button.ClickEvent;
 import com.vaadin.ui.UI;
 
 /**
@@ -23,9 +22,7 @@ public class ButtonClickTest {
     public void clickDetachedButton() {
         Button b = new Button();
         AtomicInteger counter = new AtomicInteger(0);
-        b.addClickListener((ClickEvent event) -> {
-            counter.incrementAndGet();
-        });
+        b.addClickListener(e -> counter.incrementAndGet());
 
         b.click();
         assertEquals(1, counter.get());
@@ -65,8 +62,6 @@ public class ButtonClickTest {
 
     private void addClickListener(Button b) {
         clicked = false;
-        b.addClickListener((ClickEvent ev) -> {
-            clicked = true;
-        });
+        b.addClickListener(e -> clicked = true);
     }
 }
diff --git a/server/src/test/java/com/vaadin/tests/server/component/window/AttachDetachWindowTest.java b/server/src/test/java/com/vaadin/tests/server/component/window/AttachDetachWindowTest.java
index cd7570e7b6..50385c5aed 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/window/AttachDetachWindowTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/window/AttachDetachWindowTest.java
@@ -3,15 +3,12 @@ package com.vaadin.tests.server.component.window;
 import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
-import org.junit.Assert;
 import org.junit.Test;
 
 import com.vaadin.server.ClientConnector;
 import com.vaadin.server.VaadinRequest;
 import com.vaadin.server.VaadinSession;
 import com.vaadin.tests.util.AlwaysLockedVaadinSession;
-import com.vaadin.ui.HasComponents.ComponentAttachEvent;
-import com.vaadin.ui.HasComponents.ComponentDetachEvent;
 import com.vaadin.ui.Label;
 import com.vaadin.ui.UI;
 import com.vaadin.ui.VerticalLayout;
@@ -222,12 +219,10 @@ public class AttachDetachWindowTest {
         final Window window = new Window();
 
         final boolean[] eventFired = new boolean[1];
-        ui.addComponentAttachListener((ComponentAttachEvent event) -> {
-            eventFired[0] = event.getAttachedComponent().equals(window);
-        });
+        ui.addComponentAttachListener(
+                e -> eventFired[0] = e.getAttachedComponent().equals(window));
         ui.addWindow(window);
-        assertTrue("Attach event is not fired for added window",
-                eventFired[0]);
+        assertTrue("Attach event is not fired for added window", eventFired[0]);
     }
 
     @Test
@@ -236,9 +231,8 @@ public class AttachDetachWindowTest {
         final Window window = new Window();
 
         final boolean[] eventFired = new boolean[1];
-        ui.addComponentDetachListener((ComponentDetachEvent event) -> {
-            eventFired[0] = event.getDetachedComponent().equals(window);
-        });
+        ui.addComponentDetachListener(
+                e -> eventFired[0] = e.getDetachedComponent().equals(window));
         ui.addWindow(window);
         ui.removeWindow(window);
 
diff --git a/server/src/test/java/com/vaadin/tests/server/navigator/NavigatorTest.java b/server/src/test/java/com/vaadin/tests/server/navigator/NavigatorTest.java
index 2a756da1cb..ee520a78f9 100644
--- a/server/src/test/java/com/vaadin/tests/server/navigator/NavigatorTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/navigator/NavigatorTest.java
@@ -1283,9 +1283,7 @@ public class NavigatorTest {
         navigator.navigateTo("view1");
 
         AtomicInteger leaveCount = new AtomicInteger(0);
-        navigator.runAfterLeaveConfirmation(() -> {
-            leaveCount.incrementAndGet();
-        });
+        navigator.runAfterLeaveConfirmation(() -> leaveCount.incrementAndGet());
         assertEquals(0, leaveCount.get());
         eventRef.get().navigate();
         assertEquals(1, leaveCount.get());
diff --git a/server/src/test/java/com/vaadin/ui/CheckBoxTest.java b/server/src/test/java/com/vaadin/ui/CheckBoxTest.java
index d2c280f12d..076c129914 100644
--- a/server/src/test/java/com/vaadin/ui/CheckBoxTest.java
+++ b/server/src/test/java/com/vaadin/ui/CheckBoxTest.java
@@ -49,9 +49,8 @@ public class CheckBoxTest {
         CheckBox cb = new CheckBox();
         ui.setContent(cb);
         AtomicBoolean userOriginated = new AtomicBoolean(false);
-        cb.addValueChangeListener(e -> {
-            userOriginated.set(e.isUserOriginated());
-        });
+        cb.addValueChangeListener(
+                e -> userOriginated.set(e.isUserOriginated()));
         ComponentTest.syncToClient(cb);
         ServerRpcManager.getRpcProxy(cb, CheckBoxServerRpc.class)
                 .setChecked(true, new MouseEventDetails());
@@ -69,9 +68,8 @@ public class CheckBoxTest {
         CheckBox cb = new CheckBox();
         ui.setContent(cb);
         AtomicBoolean userOriginated = new AtomicBoolean(true);
-        cb.addValueChangeListener(e -> {
-            userOriginated.set(e.isUserOriginated());
-        });
+        cb.addValueChangeListener(
+                e -> userOriginated.set(e.isUserOriginated()));
         cb.setValue(true);
         assertFalse(userOriginated.get());
         userOriginated.set(true);