private ImmutableList<TypeVariableName> typeVariableNames() {
      return context.autoValueClass().getTypeParameters().stream()
          .map(TypeVariableName::get)
          .collect(toImmutableList());
    }
An extension that implements the {@link com.google.auto.value.extension.memoized.Memoized}
contract.
value/src/main/java/com/google/auto/value/extension/memoized/processor/MemoizeExtension.java