Clean up some code quality issues

This removes some qualifiers that aren't necessary (e.g. public/abstract on interfaces, private on enum constructors, final on private methods, static on nested interfaces/enums), uses Java 8 lambdas and features where that's an improvement

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=177182945

java/google/registry/batch/DeleteContactsAndHostsAction.java

@@ -536,7 +536,7 @@ public class DeleteContactsAndHostsAction implements Runnable {
       private final String counterFormat;
       private final OperationResult operationResult;
 
-      private Type(String counterFormat, OperationResult operationResult) {
+      Type(String counterFormat, OperationResult operationResult) {
         this.counterFormat = counterFormat;
         this.operationResult = operationResult;
       }

java/google/registry/batch/DeleteProberDataAction.java

@@ -138,7 +138,7 @@ public class DeleteProberDataAction implements Runnable {
         if (proberRoidSuffixes.contains(roidSuffix)) {
           deleteDomain(key);
         } else {
-          getContext().incrementCounter(String.format("skipped, non-prober data"));
+          getContext().incrementCounter("skipped, non-prober data");
         }
       } catch (Throwable t) {
         logger.severefmt(t, "Error while deleting prober data for key %s", key);

java/google/registry/batch/MapreduceEntityCleanupAction.java

@@ -220,11 +220,10 @@ public class MapreduceEntityCleanupAction implements Runnable {
         errorCount++;
       }
       logger.infofmt("%s: %s", actualJobId, error.orElse("deletion requested"));
-      if (payloadChunkBuilder.isPresent()) {
-        payloadChunkBuilder
-            .get()
-            .append(String.format("%s: %s\n", actualJobId, error.orElse("deletion requested")));
-      }
+      payloadChunkBuilder.ifPresent(
+          stringBuilder ->
+              stringBuilder.append(
+                  String.format("%s: %s\n", actualJobId, error.orElse("deletion requested"))));
     }
     logger.infofmt(
         "successfully requested async deletion of %s job(s); errors received on %s",

java/google/registry/batch/VerifyEntityIntegrityAction.java

@@ -136,10 +136,9 @@ public class VerifyEntityIntegrityAction implements Runnable {
             getInputs())));
   }
 
-  private static ImmutableSet<Input<? extends Object>> getInputs() {
-    ImmutableSet.Builder<Input<? extends Object>> builder =
-        new ImmutableSet.Builder<Input<? extends Object>>()
-            .add(EppResourceInputs.createIndexInput());
+  private static ImmutableSet<Input<?>> getInputs() {
+    ImmutableSet.Builder<Input<?>> builder =
+        new ImmutableSet.Builder<Input<?>>().add(EppResourceInputs.createIndexInput());
     RESOURCE_CLASSES
         .stream()
         .map(clazz -> new DatastoreKeyInput(getKind(clazz), NUM_SHARDS))
@@ -153,7 +152,7 @@ public class VerifyEntityIntegrityAction implements Runnable {
    * contact), which is used to check {@link ForeignKeyIndex} constraints, and one that is common
    * for all EppResources, to check {@link EppResourceIndex} constraints.
    */
-  private static enum EntityKind {
+  private enum EntityKind {
     DOMAIN,
     APPLICATION,
     CONTACT,