public Set<ExecutableElement> consumeBuilderMethods(Context context) {
    return ImmutableSet.of();
  }
Returns a possibly empty set of abstract methods that this Extension intends to implement. This
will prevent AutoValue from generating an implementation, in cases where it would have, and it
will also avoid complaints about abstract methods that AutoValue doesn't expect. The default
set returned by this method is empty.

<p>Each returned method must be one of the abstract methods in {@link
Context#builderAbstractMethods()}.

@param context the Context of the code generation for this class.
value/src/main/java/com/google/auto/value/extension/AutoValueExtension.java