Remove redundant "static" modifier from enums

Change-Id: If8563a3b2848ffd918b74fa3167d1ee230ba1bac

java/com/google/gerrit/server/change/MergeabilityCacheImpl.java

@@ -134,7 +134,7 @@ public class MergeabilityCacheImpl implements MergeabilityCache {
           .toString();
     }
 
-    static enum Serializer implements CacheSerializer<EntryKey> {
+    enum Serializer implements CacheSerializer<EntryKey> {
       INSTANCE;
 
       private static final Converter<String, SubmitType> SUBMIT_TYPE_CONVERTER =

java/com/google/gerrit/server/notedb/ChangeNotesCache.java

@@ -77,7 +77,7 @@ public class ChangeNotesCache {
     abstract ObjectId id();
 
     @VisibleForTesting
-    static enum Serializer implements CacheSerializer<Key> {
+    enum Serializer implements CacheSerializer<Key> {
       INSTANCE;
 
       @Override

java/com/google/gerrit/server/notedb/ChangeNotesState.java

@@ -430,7 +430,7 @@ public abstract class ChangeNotesState {
     abstract ChangeNotesState build();
   }
 
-  static enum Serializer implements CacheSerializer<ChangeNotesState> {
+  enum Serializer implements CacheSerializer<ChangeNotesState> {
     INSTANCE;
 
     @VisibleForTesting static final Gson GSON = OutputFormat.JSON_COMPACT.newGson();

java/com/google/gerrit/server/query/change/ConflictKey.java

@@ -61,7 +61,7 @@ public abstract class ConflictKey {
 
   public abstract boolean contentMerge();
 
-  public static enum Serializer implements CacheSerializer<ConflictKey> {
+  public enum Serializer implements CacheSerializer<ConflictKey> {
     INSTANCE;
 
     private static final Converter<String, SubmitType> SUBMIT_TYPE_CONVERTER =

java/com/google/gerrit/server/schema/Schema_159.java

@@ -23,7 +23,7 @@ import com.google.inject.Provider;
 /** Migrate draft changes to private or wip changes. */
 public class Schema_159 extends SchemaVersion {
 
-  private static enum DraftWorkflowMigrationStrategy {
+  private enum DraftWorkflowMigrationStrategy {
     PRIVATE,
     WORK_IN_PROGRESS
   }