} else {
      return TypeToken.of(Object.class);
    }
  }

  private <T> T newDefaultReturningProxy(final TypeToken<T> type) {
    return new DummyProxy() {
      @Override
      <R> @Nullable R dummyReturnValue(TypeToken<R> returnType) {
        return getDefaultValue(returnType);
      }
    }.newProxy(type);
  }

    } else {
      return TypeToken.of(Object.class);
    }
  }

  private <T> T newDefaultReturningProxy(final TypeToken<T> type) {
    return new DummyProxy() {
      @Override
      <R> @Nullable R dummyReturnValue(TypeToken<R> returnType) {
        return getDefaultValue(returnType);
      }
    }.newProxy(type);
  }

      super(factory + " returns null and cannot be used to test instance methods.");
    }
  }

  private static final class SerializableDummyProxy extends DummyProxy implements Serializable {

    private final transient ClassSanityTester tester;

    SerializableDummyProxy(ClassSanityTester tester) {
      this.tester = tester;
    }

    @Override