waitTimeoutOnResponseBackpressureMs should be gt 0

[gaozhangmin]

update timeOut >= 0 to timeout > 0, it make no sense executing back pressure when waitTimeoutOnBackpressureMillis=0

[hangc0276]

0 to allow request to fail immediately

[zymap]

timeout is 0 should fail immediately, it is expected.

[gaozhangmin]

Is it ok when timeout is 0 and blacklistedChannels = Optional.empty() ? @zymap @hangc0276

bookkeeper/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieRequestProcessor.java

Lines 173 to 179 in 396ec12

	if (waitTimeoutOnBackpressureMillis > 0) {
	blacklistedChannels = Optional.of(CacheBuilder.newBuilder()
	.expireAfterWrite(waitTimeoutOnBackpressureMillis, TimeUnit.MILLISECONDS)
	.build());
	} else {
	blacklistedChannels = Optional.empty();
	}