Enable and fix Eclipse warnings about redundant type arguments

Since Java 7 it is possible to replace the type arguments required to
invoke the constructor of a generic class with an empty set of type
parameters (<>) as long as the compiler can infer the type arguments
from the context [1].

Enable the Eclipse warning about redundant type arguments, and remove
the ones it warns about.

[1] http://goo.gl/SG21kM

Change-Id: I422882949a6a6a57391580d881f73120b2843a0e

gerrit-server/src/main/java/com/google/gerrit/server/query/Predicate.java

@@ -92,7 +92,7 @@ public abstract class Predicate<T> {
       //
       return that.getChild(0);
     }
-    return new NotPredicate<T>(that);
+    return new NotPredicate<>(that);
   }
 
   /** Get the children of this predicate, if any. */