code: @Override
      public void setClientID(String clientID) {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.entry(this, tc, "setClientID", clientID);
  
          // Make empty and null look the same.
          if ("".equals(clientID))
              clientID = null;
          jcaManagedConnectionFactory.setClientID(clientID);
  
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.exit(this, tc, "setClientID");
      }
docs: /*
  default client id is null.