Clarify the difference (if any) between JMSException.getLinkedException() and JMSException.getCause()

JMSException.getLinkedException() is usually containing the provider-specific Exception object, but there's also already the inherited Exception.getCause() method.
JMS Providers could potentially return different things in each method, which would be confusing.

Also, 'exception un-nesting code' would typically use Exception.getCause() multiple times until getCause() returns null to get to the root cause which then usually contains a better error description. Since this 'exception un-nesting code' could catch exceptions from multiple API's it would be nice if JMS behaves just like any other library (let getCause() return the cause of the exception).

My proposal would be to require JMS providers to implement JMSException.getCause() like this:

@Override
    public Throwable getCause()
    {
        return getLinkedException();
    }

That way, JMS wouldn't play a special role when interpreting the cause of an exception.

Affected Versions

[2.0]

Start by reviewing the JMSException methods named in the issue and the affected JMS 2.0 API behavior. Determine whether getCause() must mirror getLinkedException() and what provider behavior the specification should require; done means the relationship is unambiguously defined.