Use final modifier where appropriate

Change-Id: I80b73b653e97904605dc62484a7448f3bfbf7226

25 files changed, 49 insertions, 50 deletions

diff --git a/server/src/main/java/com/vaadin/ui/AbsoluteLayout.java b/server/src/main/java/com/vaadin/ui/AbsoluteLayout.java
index e968568a09..49d020d32f 100644
--- a/server/src/main/java/com/vaadin/ui/AbsoluteLayout.java
+++ b/server/src/main/java/com/vaadin/ui/AbsoluteLayout.java
@@ -55,12 +55,11 @@ public class AbsoluteLayout extends AbstractLayout
     private static final String ATTR_Z_INDEX = ":z-index";
 
     private final AbsoluteLayoutServerRpc rpc = (MouseEventDetails mouseDetails,
-            Connector clickedConnector) -> {
-        fireEvent(LayoutClickEvent.createEvent(AbsoluteLayout.this,
-                mouseDetails, clickedConnector));
-    };
+            Connector clickedConnector) -> fireEvent(
+                    LayoutClickEvent.createEvent(AbsoluteLayout.this,
+                            mouseDetails, clickedConnector));
     // Maps each component to a position
-    private LinkedHashMap<Component, ComponentPosition> componentToCoordinates = new LinkedHashMap<>();
+    private final LinkedHashMap<Component, ComponentPosition> componentToCoordinates = new LinkedHashMap<>();
 
     /**
      * Creates an AbsoluteLayout with full size.
diff --git a/server/src/main/java/com/vaadin/ui/AbstractColorPicker.java b/server/src/main/java/com/vaadin/ui/AbstractColorPicker.java
index 7f79cecf55..7a40798815 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractColorPicker.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractColorPicker.java
@@ -75,7 +75,7 @@ public abstract class AbstractColorPicker extends AbstractField<Color> {
         /** A simple popup with only the swatches (palette) tab. */
         POPUP_SIMPLE("simple");
 
-        private String style;
+        private final String style;
 
         PopupStyle(String styleName) {
             style = styleName;
diff --git a/server/src/main/java/com/vaadin/ui/AbstractJavaScriptComponent.java b/server/src/main/java/com/vaadin/ui/AbstractJavaScriptComponent.java
index 580754be01..8e70e9cb03 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractJavaScriptComponent.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractJavaScriptComponent.java
@@ -149,7 +149,7 @@ import elemental.json.JsonValue;
  * @since 7.0.0
  */
 public abstract class AbstractJavaScriptComponent extends AbstractComponent {
-    private JavaScriptCallbackHelper callbackHelper = new JavaScriptCallbackHelper(
+    private final JavaScriptCallbackHelper callbackHelper = new JavaScriptCallbackHelper(
             this);
 
     @Override
diff --git a/server/src/main/java/com/vaadin/ui/AbstractOrderedLayout.java b/server/src/main/java/com/vaadin/ui/AbstractOrderedLayout.java
index 6c995611fb..6858a18999 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractOrderedLayout.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractOrderedLayout.java
@@ -45,10 +45,10 @@ public abstract class AbstractOrderedLayout extends AbstractLayout
         LayoutClickNotifier, Layout.MarginHandler {
 
     private final AbstractOrderedLayoutServerRpc rpc = (
-            MouseEventDetails mouseDetails, Connector clickedConnector) -> {
-        fireEvent(LayoutClickEvent.createEvent(AbstractOrderedLayout.this,
-                mouseDetails, clickedConnector));
-    };
+            MouseEventDetails mouseDetails,
+            Connector clickedConnector) -> fireEvent(
+                    LayoutClickEvent.createEvent(AbstractOrderedLayout.this,
+                            mouseDetails, clickedConnector));
 
     public static final Alignment ALIGNMENT_DEFAULT = Alignment.TOP_LEFT;
 
diff --git a/server/src/main/java/com/vaadin/ui/AbstractSplitPanel.java b/server/src/main/java/com/vaadin/ui/AbstractSplitPanel.java
index 73bedc8470..e7a66cebe5 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractSplitPanel.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractSplitPanel.java
@@ -54,7 +54,7 @@ public abstract class AbstractSplitPanel extends AbstractComponentContainer {
     private Unit posMinUnit;
     private Unit posMaxUnit;
 
-    private AbstractSplitPanelRpc rpc = new AbstractSplitPanelRpc() {
+    private final AbstractSplitPanelRpc rpc = new AbstractSplitPanelRpc() {
 
         @Override
         public void splitterClick(MouseEventDetails mouseDetails) {
diff --git a/server/src/main/java/com/vaadin/ui/ConnectorTracker.java b/server/src/main/java/com/vaadin/ui/ConnectorTracker.java
index fd2c0029d1..2ba6f5e895 100644
--- a/server/src/main/java/com/vaadin/ui/ConnectorTracker.java
+++ b/server/src/main/java/com/vaadin/ui/ConnectorTracker.java
@@ -68,8 +68,8 @@ import elemental.json.JsonObject;
 public class ConnectorTracker implements Serializable {
 
     private final HashMap<String, ClientConnector> connectorIdToConnector = new HashMap<>();
-    private Set<ClientConnector> dirtyConnectors = new HashSet<>();
-    private Set<ClientConnector> uninitializedConnectors = new HashSet<>();
+    private final Set<ClientConnector> dirtyConnectors = new HashSet<>();
+    private final Set<ClientConnector> uninitializedConnectors = new HashSet<>();
 
     /**
      * Connectors that have been unregistered and should be cleaned up the next
@@ -80,7 +80,7 @@ public class ConnectorTracker implements Serializable {
 
     private boolean writingResponse = false;
 
-    private UI uI;
+    private final UI uI;
     private transient Map<ClientConnector, JsonObject> diffStates = new HashMap<>();
 
     /** Maps connectorIds to a map of named StreamVariables */
@@ -96,7 +96,7 @@ public class ConnectorTracker implements Serializable {
      * @see #getCurrentSyncId()
      * @see #cleanConcurrentlyRemovedConnectorIds(long)
      */
-    private TreeMap<Integer, Set<String>> syncIdToUnregisteredConnectorIds = new TreeMap<>();
+    private final TreeMap<Integer, Set<String>> syncIdToUnregisteredConnectorIds = new TreeMap<>();
 
     /**
      * Gets a logger for this class
diff --git a/server/src/main/java/com/vaadin/ui/DragAndDropWrapper.java b/server/src/main/java/com/vaadin/ui/DragAndDropWrapper.java
index 7f2e558220..4b9a7afbfb 100644
--- a/server/src/main/java/com/vaadin/ui/DragAndDropWrapper.java
+++ b/server/src/main/java/com/vaadin/ui/DragAndDropWrapper.java
@@ -351,7 +351,7 @@ public class DragAndDropWrapper extends CustomComponent
 
     final class ProxyReceiver implements StreamVariable {
 
-        private String id;
+        private final String id;
         private Html5File file;
 
         public ProxyReceiver(String id, Html5File file) {
@@ -425,7 +425,7 @@ public class DragAndDropWrapper extends CustomComponent
         class ReceivingEventWrapper implements StreamingErrorEvent,
                 StreamingEndEvent, StreamingStartEvent, StreamingProgressEvent {
 
-            private StreamingEvent wrappedEvent;
+            private final StreamingEvent wrappedEvent;
 
             ReceivingEventWrapper(StreamingEvent e) {
                 wrappedEvent = e;
diff --git a/server/src/main/java/com/vaadin/ui/Grid.java b/server/src/main/java/com/vaadin/ui/Grid.java
index b738b71323..63c8fe3e6f 100644
--- a/server/src/main/java/com/vaadin/ui/Grid.java
+++ b/server/src/main/java/com/vaadin/ui/Grid.java
@@ -650,8 +650,8 @@ public class Grid<T> extends AbstractSingleSelect<T> implements HasComponents {
      */
     public static class DetailsManager<T> extends AbstractGridExtension<T> {
 
-        private Set<T> visibleDetails = new HashSet<>();
-        private Map<T, Component> components = new HashMap<>();
+        private final Set<T> visibleDetails = new HashSet<>();
+        private final Map<T, Component> components = new HashMap<>();
         private DetailsGenerator<T> generator;
 
         /**
@@ -1821,17 +1821,17 @@ public class Grid<T> extends AbstractSingleSelect<T> implements HasComponents {
         }
     };
 
-    private Set<Column<T, ?>> columnSet = new LinkedHashSet<>();
-    private Map<String, Column<T, ?>> columnKeys = new HashMap<>();
+    private final Set<Column<T, ?>> columnSet = new LinkedHashSet<>();
+    private final Map<String, Column<T, ?>> columnKeys = new HashMap<>();
 
-    private List<SortOrder<Column<T, ?>>> sortOrder = new ArrayList<>();
-    private DetailsManager<T> detailsManager;
-    private Set<Component> extensionComponents = new HashSet<>();
+    private final List<SortOrder<Column<T, ?>>> sortOrder = new ArrayList<>();
+    private final DetailsManager<T> detailsManager;
+    private final Set<Component> extensionComponents = new HashSet<>();
     private StyleGenerator<T> styleGenerator = item -> null;
     private DescriptionGenerator<T> descriptionGenerator;
 
-    private Header header = new HeaderImpl();
-    private Footer footer = new FooterImpl();
+    private final Header header = new HeaderImpl();
+    private final Footer footer = new FooterImpl();
 
     private int counter = 0;
 
diff --git a/server/src/main/java/com/vaadin/ui/Html5File.java b/server/src/main/java/com/vaadin/ui/Html5File.java
index b3fcdb826f..b4434e75c9 100644
--- a/server/src/main/java/com/vaadin/ui/Html5File.java
+++ b/server/src/main/java/com/vaadin/ui/Html5File.java
@@ -27,10 +27,10 @@ import com.vaadin.server.StreamVariable;
  */
 public class Html5File implements Serializable {
 
-    private String name;
-    private long size;
+    private final String name;
+    private final long size;
     private StreamVariable streamVariable;
-    private String type;
+    private final String type;
 
     Html5File(String name, long size, String mimeType) {
         this.name = name;
diff --git a/server/src/main/java/com/vaadin/ui/LoadingIndicatorConfiguration.java b/server/src/main/java/com/vaadin/ui/LoadingIndicatorConfiguration.java
index 32b9356d76..bd56036aee 100644
--- a/server/src/main/java/com/vaadin/ui/LoadingIndicatorConfiguration.java
+++ b/server/src/main/java/com/vaadin/ui/LoadingIndicatorConfiguration.java
@@ -83,7 +83,7 @@ public interface LoadingIndicatorConfiguration extends Serializable {
 
 class LoadingIndicatorConfigurationImpl
         implements LoadingIndicatorConfiguration {
-    private UI ui;
+    private final UI ui;
 
     public LoadingIndicatorConfigurationImpl(UI ui) {
         this.ui = ui;
diff --git a/server/src/main/java/com/vaadin/ui/LoginForm.java b/server/src/main/java/com/vaadin/ui/LoginForm.java
index 74432d001a..9acd0735b1 100644
--- a/server/src/main/java/com/vaadin/ui/LoginForm.java
+++ b/server/src/main/java/com/vaadin/ui/LoginForm.java
@@ -62,7 +62,7 @@ public class LoginForm extends AbstractSingleComponentContainer {
      */
     public static class LoginEvent extends Component.Event {
 
-        private Map<String, String> params;
+        private final Map<String, String> params;
 
         /**
          * Creates a login event using the given source and the given
diff --git a/server/src/main/java/com/vaadin/ui/Notification.java b/server/src/main/java/com/vaadin/ui/Notification.java
index 536598448b..7ee78fb807 100644
--- a/server/src/main/java/com/vaadin/ui/Notification.java
+++ b/server/src/main/java/com/vaadin/ui/Notification.java
@@ -70,7 +70,7 @@ public class Notification implements Serializable {
          */
         ASSISTIVE_NOTIFICATION("assistive");
 
-        private String style;
+        private final String style;
 
         Type(String style) {
             this.style = style;
diff --git a/server/src/main/java/com/vaadin/ui/NotificationConfiguration.java b/server/src/main/java/com/vaadin/ui/NotificationConfiguration.java
index f7591af13c..0062bb969f 100644
--- a/server/src/main/java/com/vaadin/ui/NotificationConfiguration.java
+++ b/server/src/main/java/com/vaadin/ui/NotificationConfiguration.java
@@ -118,7 +118,7 @@ public interface NotificationConfiguration extends Serializable {
 
 class NotificationConfigurationImpl implements NotificationConfiguration {
 
-    private UI ui;
+    private final UI ui;
 
     public NotificationConfigurationImpl(UI ui) {
         this.ui = ui;
diff --git a/server/src/main/java/com/vaadin/ui/PushConfiguration.java b/server/src/main/java/com/vaadin/ui/PushConfiguration.java
index cad96a5952..bb722ec2d2 100644
--- a/server/src/main/java/com/vaadin/ui/PushConfiguration.java
+++ b/server/src/main/java/com/vaadin/ui/PushConfiguration.java
@@ -165,7 +165,7 @@ public interface PushConfiguration extends Serializable {
 }
 
 class PushConfigurationImpl implements PushConfiguration {
-    private UI ui;
+    private final UI ui;
 
     public PushConfigurationImpl(UI ui) {
         this.ui = ui;
diff --git a/server/src/main/java/com/vaadin/ui/ReconnectDialogConfiguration.java b/server/src/main/java/com/vaadin/ui/ReconnectDialogConfiguration.java
index d4df9fdf28..8a36de3510 100644
--- a/server/src/main/java/com/vaadin/ui/ReconnectDialogConfiguration.java
+++ b/server/src/main/java/com/vaadin/ui/ReconnectDialogConfiguration.java
@@ -132,7 +132,7 @@ public interface ReconnectDialogConfiguration extends Serializable {
 }
 
 class ReconnectDialogConfigurationImpl implements ReconnectDialogConfiguration {
-    private UI ui;
+    private final UI ui;
 
     public ReconnectDialogConfigurationImpl(UI ui) {
         this.ui = ui;
diff --git a/server/src/main/java/com/vaadin/ui/TabSheet.java b/server/src/main/java/com/vaadin/ui/TabSheet.java
index 5623166357..7ad40c2771 100644
--- a/server/src/main/java/com/vaadin/ui/TabSheet.java
+++ b/server/src/main/java/com/vaadin/ui/TabSheet.java
@@ -1101,7 +1101,7 @@ public class TabSheet extends AbstractComponentContainer
      */
     public class TabSheetTabImpl implements Tab {
 
-        private TabState tabState;
+        private final TabState tabState;
 
         private Focusable defaultFocus;
 
diff --git a/server/src/main/java/com/vaadin/ui/TooltipConfiguration.java b/server/src/main/java/com/vaadin/ui/TooltipConfiguration.java
index b5af10961b..1bf9fd7b81 100644
--- a/server/src/main/java/com/vaadin/ui/TooltipConfiguration.java
+++ b/server/src/main/java/com/vaadin/ui/TooltipConfiguration.java
@@ -123,7 +123,7 @@ public interface TooltipConfiguration extends Serializable {
 }
 
 class TooltipConfigurationImpl implements TooltipConfiguration {
-    private UI ui;
+    private final UI ui;
 
     public TooltipConfigurationImpl(UI ui) {
         this.ui = ui;
diff --git a/server/src/main/java/com/vaadin/ui/components/colorpicker/ColorPickerHistory.java b/server/src/main/java/com/vaadin/ui/components/colorpicker/ColorPickerHistory.java
index a32378aeaf..ae1c304fd2 100644
--- a/server/src/main/java/com/vaadin/ui/components/colorpicker/ColorPickerHistory.java
+++ b/server/src/main/java/com/vaadin/ui/components/colorpicker/ColorPickerHistory.java
@@ -40,7 +40,7 @@ public class ColorPickerHistory extends CustomField<Color> {
     private static final int COLUMNS = 15;
 
     /** Temporary color history for when the component is detached. */
-    private ArrayBlockingQueue<Color> tempHistory = new ArrayBlockingQueue<>(
+    private final ArrayBlockingQueue<Color> tempHistory = new ArrayBlockingQueue<>(
             ROWS * COLUMNS);
 
     @Override
diff --git a/server/src/main/java/com/vaadin/ui/components/colorpicker/ColorPickerSelect.java b/server/src/main/java/com/vaadin/ui/components/colorpicker/ColorPickerSelect.java
index 20d68da0fa..ec200082ab 100644
--- a/server/src/main/java/com/vaadin/ui/components/colorpicker/ColorPickerSelect.java
+++ b/server/src/main/java/com/vaadin/ui/components/colorpicker/ColorPickerSelect.java
@@ -38,7 +38,7 @@ public class ColorPickerSelect extends CustomField<Color> {
         ALL("All colors"), RED("Red colors"), GREEN("Green colors"), BLUE(
                 "Blue colors");
 
-        private String caption;
+        private final String caption;
 
         ColorRange(String caption) {
             this.caption = caption;
diff --git a/server/src/main/java/com/vaadin/ui/components/grid/StaticSection.java b/server/src/main/java/com/vaadin/ui/components/grid/StaticSection.java
index eb02be2bbc..678ab2a935 100644
--- a/server/src/main/java/com/vaadin/ui/components/grid/StaticSection.java
+++ b/server/src/main/java/com/vaadin/ui/components/grid/StaticSection.java
@@ -150,8 +150,8 @@ public abstract class StaticSection<ROW extends StaticSection.StaticRow<?>>
      */
     abstract static class StaticCell implements Serializable {
 
-        private CellState cellState = new CellState();
-        private StaticRow<?> row;
+        private final CellState cellState = new CellState();
+        private final StaticRow<?> row;
 
         protected StaticCell(StaticRow<?> row) {
             this.row = row;
diff --git a/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java b/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java
index 00fb32392c..5b0968bae6 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/DesignAttributeHandler.java
@@ -430,7 +430,7 @@ public class DesignAttributeHandler implements Serializable {
      * @author Vaadin Ltd
      */
     private static class AttributeCacheEntry implements Serializable {
-        private Map<String, Method[]> accessMethods = new ConcurrentHashMap<>();
+        private final Map<String, Method[]> accessMethods = new ConcurrentHashMap<>();
 
         private void addAttribute(String attribute, Method getter,
                 Method setter) {
diff --git a/server/src/main/java/com/vaadin/ui/declarative/DesignContext.java b/server/src/main/java/com/vaadin/ui/declarative/DesignContext.java
index c8e794c46a..761c7edd04 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/DesignContext.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/DesignContext.java
@@ -686,9 +686,9 @@ public class DesignContext implements Serializable {
      * @author Vaadin Ltd
      */
     public class ComponentCreatedEvent implements Serializable {
-        private String localId;
-        private Component component;
-        private DesignContext context;
+        private final String localId;
+        private final Component component;
+        private final DesignContext context;
 
         /**
          * Creates a new instance of ComponentCreatedEvent
diff --git a/server/src/main/java/com/vaadin/ui/declarative/converters/DesignEnumConverter.java b/server/src/main/java/com/vaadin/ui/declarative/converters/DesignEnumConverter.java
index 93ccee3f37..a32c68998f 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/converters/DesignEnumConverter.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/converters/DesignEnumConverter.java
@@ -33,7 +33,7 @@ import com.vaadin.ui.declarative.DesignAttributeHandler;
 public class DesignEnumConverter<T extends Enum>
         implements Converter<String, T> {
 
-    private Class<T> type;
+    private final Class<T> type;
 
     /**
      * Creates a converter for the given enum type.
diff --git a/server/src/main/java/com/vaadin/ui/declarative/converters/DesignResourceConverter.java b/server/src/main/java/com/vaadin/ui/declarative/converters/DesignResourceConverter.java
index ef6e10ef5c..c03d3750d1 100644
--- a/server/src/main/java/com/vaadin/ui/declarative/converters/DesignResourceConverter.java
+++ b/server/src/main/java/com/vaadin/ui/declarative/converters/DesignResourceConverter.java
@@ -170,7 +170,7 @@ public class DesignResourceConverter implements Converter<String, Resource> {
             return ((ExternalResource) value).getURL();
         }
 
-        private static Map<Class<? extends Resource>, ResourceConverterByProtocol> typeToConverter = new HashMap<>();
+        private static final Map<Class<? extends Resource>, ResourceConverterByProtocol> typeToConverter = new HashMap<>();
         static {
             typeToConverter.put(ExternalResource.class, HTTP);
             // ^ any of non-specialized would actually work
diff --git a/server/src/main/java/com/vaadin/ui/renderers/ClickableRenderer.java b/server/src/main/java/com/vaadin/ui/renderers/ClickableRenderer.java
index 3073517b65..8686c391c5 100644
--- a/server/src/main/java/com/vaadin/ui/renderers/ClickableRenderer.java
+++ b/server/src/main/java/com/vaadin/ui/renderers/ClickableRenderer.java
@@ -70,8 +70,8 @@ public abstract class ClickableRenderer<T, V> extends AbstractRenderer<T, V> {
      */
     public static class RendererClickEvent<T> extends ClickEvent {
 
-        private T item;
-        private Column column;
+        private final T item;
+        private final Column column;
 
         protected RendererClickEvent(Grid<T> source, T item, Column column,
                 MouseEventDetails mouseEventDetails) {