[Java Client] Avoid sending flow requests with zero permits

[BewareMyPower]

Motivation

It's the Java client side fix for #10506.

When broker receives a FLOW request with zero permit, an IllegalArgumentException will be thrown in ServerCnx#handleFlow and then the connection will be closed so that the consumer will reconnect to the broker. If resume() was called for a zero queue consumer, the permits may be zero and trigger a reconnection. The frequent reconnections may cause messages repeated or out of order.

Modifications

• Validate the permits of a FLOW command before sending it.
• Add a test that a zero queue consumer resumes and pauses for each message periodically. Before this PR, there's a great chance that the received messages are repeated or out of order, even a ACK was sent.

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests ZeroQueueSizeTest#testPauseAndResumeNoReconnection.

[BewareMyPower]

/pulsarbot run-failure-checks