code: protected synchronized void unjoin(SIXAResource resource)
     {
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(this, tc, "unjoin", resource);
        resourcesJoinedToThisResource.remove(resource);
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(this, tc, "unjoin");
     }
docs: Called when another instance is un-joining from us.
  @param resource