UniformRandomBackOffPolicy is throwing IllegalArgumentException on calling `backOff` when maxBackOffPeriod is less than minBackOffPeriod.

[LokeshAlamuri]

Scenario:

UniformRandomBackOffPolicy is throwing IllegalArgumentException on calling backOff when maxBackOffPeriod is less than minBackOffPeriod.

Version Tested:

2.0.9

Junit to Replicate::

maxBackOff < minBackOff

@Test
public void testMaxBackOffLessThanMinBackOff() {
	UniformRandomBackOffPolicy backOffPolicy = new UniformRandomBackOffPolicy();
	int minBackOff = 1000;
	int maxBackOff = 10;
	backOffPolicy.setMinBackOffPeriod(minBackOff);
	backOffPolicy.setMaxBackOffPeriod(maxBackOff);
	UniformRandomBackOffPolicy withSleeper = backOffPolicy.withSleeper(new Sleeper() {
		@Override
		public void sleep(long backOffPeriod) throws InterruptedException {
			// do nothing;
		}
	});

	assertThatExceptionOfType(IllegalArgumentException.class).isThrownBy(() -> withSleeper.backOff(null));
}

Possible fix:

Following scenarios are addressed when the UniformRandomBackOffPolicy is not configured properly.

1. maxBackOff is less than or equal to zero.
2. minackOff is less than or equal to zero.
3. maxBackOff is equal to minBackOff.

Similarly, when maxBackOff is less than minBackOff could be validated and provide some default value.

[LokeshAlamuri]

Please review the following PR to fix the reported issue. Please give your comments.
#465