code: protected void unsetUserTransaction(ServiceReference<UserTransaction> ref) {
          if (TraceComponent.isAnyTracingEnabled() && LoggingUtil.SESSION_LOGGER_WAS.isLoggable(Level.FINE)) {
              LoggingUtil.SESSION_LOGGER_WAS.logp(Level.FINE, methodClassName, "unsetUserTransaction", "unsetting " + ref);
          }
          userTransactionRef.unsetReference(ref);
      }
docs: Declarative Services method for unsetting the UserTransaction service reference
  
  @param ref reference to service object; type of service object is verified