@GremlinDsl.AnonymousMethod(returnTypeParameters = {"A", "E2"}, methodTypeParameters = {"A", "E2 extends java.lang.Number"})
    public default <E2 extends Number> GraphTraversal<S, E2> meanAgeOfFriendsOverride() {
        return out("knows").hasLabel("person").values("age").mean();
    }
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-annotations/src/test/resources/org/apache/tinkerpop/gremlin/process/traversal/dsl/SocialTraversalDsl.java