public void onSuccess(String result) {
      synchronized (monitor) {
        assertFalse(wasCalled);
        wasCalled = true;
        assertEquals(value, result);
      }
    }

    @Override
    public synchronized void onFailure(Throwable t) {
      synchronized (monitor) {
        assertFalse(wasCalled);
        wasCalled = true;
        assertEquals(failure, t);
      }
    }
  }

    boolean wasCalled = false; // must be set in load()
    String keyPrefix = KEY_PREFIX;
    int valuePrefix = VALUE_PREFIX;

    WatchedCreatorLoader() {}

    void reset() {
      wasCalled = false;
    }

    boolean wasCalled() {
      return wasCalled;
    }

    void setKeyPrefix(String keyPrefix) {

    fail("Should detect problem in " + FailOnOneOfTwoConstructors.class.getSimpleName());
  }

  public static class NullBounds<T extends @Nullable Object, U extends T, X> {
    boolean xWasCalled;

    public void x(X x) {
      xWasCalled = true;
      checkNotNull(x);
    }

    public void t(T t) {
      fail("Method with parameter <T extends @Nullable Object> should not be called");
    }