end() method is only called once on a resource Manager

In SimpleXAResourceProxy, a boolean prevents to call more than once the end()
method on the underlying resource manager. It is a problem when you want to
suspend/resume a transaction because in this case there is a serie of start/end
(suspend), start(resume)/end(suspend), start(resume)/end(finish), and only the
first end() is called.
I am using OracleAQ and this generates OracleXAException because after the first
resume, the transaction is not suspended and then I get an OracleXAException.
One easy fix is to add one line in the start() method to reinitialise the
boolean used in the end() method of the ResourceProxy.
#### Environment
Operating System: All
Platform: All
#### Affected Versions
[current]