code: @SuppressWarnings("unused")
      static Void throwUnsafelyIfNonNull(@Nullable Object unused,
                                         @Nullable Throwable cause) {
          throwUnsafelyIfNonNull(cause);
          return null;
      }
docs: Throws the specified {@link Throwable} if it is not {@code null}. This is a special form to be used
  for {@link CompletionStage#handle(BiFunction)}.