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

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

java/google/registry/rde/RdeReporter.java

@@ -117,8 +117,7 @@ public class RdeReporter {
     logger.infofmt("Received response:\n%s", new String(responseBytes, UTF_8));
     XjcIirdeaResponseElement response = XjcXmlTransformer.unmarshal(
         XjcIirdeaResponseElement.class, new ByteArrayInputStream(responseBytes));
-    XjcIirdeaResult result = response.getResult();
-    return result;
+    return response.getResult();
   }
 
   private URL makeReportUrl(String tld, String id) {