Messaging client hangs during shutdown

[joe-chacko]

Describe the bug
While the server is creating the SSL keystore, the messaging client restarts. During the shutdown of the messaging client a new outbound connection can be created that is then never cleaned up. The next server shutdown then hangs indefinitely.

Steps to Reproduce
This is hard to reproduce. An application must try to connect to a remote messaging engine while the server-acting-as-client is creating a new keystore.

Expected behavior
No new outbound connection should be allowed while the messaging client is shutting down.

Diagnostic information:

• OpenLiberty Version: all versions prior to 22.0.0.13
• Affected feature(s) wasJmsClient-2.0, messagingClient-3.0
• Java Version: all

[joe-chacko]

Fixed by #23574