code: public void registerCallback(UOWCallback callback)
      {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) Tr.entry(tc, "registerCallback", callback);
  
          if (!_callbacks.contains(callback))
          {
              _callbacks.add(callback);
  
              if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) Tr.debug(tc, "Number of registered Callbacks: "+_callbacks.size());
          }
  
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) Tr.exit(tc, "registerCallback");
      }
docs: Register a <code>UOWCallback</code> for LTC notifications.
  
  @param callback The UOWCallback object to register with the LocalTransaction service