Lambda usage in FutureUtils is ambigouos with Java 9

In FutureUtils the following code doesn't compile with java 9:

... = scheduledExecutor.schedule(
	() -> retryOperationWithDelay(resultFuture, operation, retries - 1, retryDelay,
	...,
	...,
	...);

The reason is that the compiler cannot determine whether the lambda should be a Runnable or a Callable<V>, resulting in incompatible bounds for the return type.