code: @Override
      public void setGatherMessages(String gatherMessages) throws JMSException {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.entry(this, tc, "setGatherMessages", gatherMessages);
  
          // Make sure null and empty are treated equally.
          if ((gatherMessages == null) || ("".equals(gatherMessages.trim())))
              gatherMessages = null;
  
          if ((gatherMessages == null) ||
              (ApiJmsConstants.GATHER_MESSAGES_OFF.equals(gatherMessages) ||
              (ApiJmsConstants.GATHER_MESSAGES_ON.equals(gatherMessages)))) {
  
              updateProperty(GATHER_MESSAGES, gatherMessages);
          }
          else {
              // bad value, throw exception
              String key = "INVALID_VALUE_CWSIA0281";
              Object[] inserts = new Object[] { GATHER_MESSAGES, gatherMessages };
              throw (JMSException) JmsErrorUtils.newThrowable(JMSException.class, key, inserts, tc);
          }
  
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.exit(this, tc, "setGatherMessages");
      }
docs: /*
  (non-Javadoc)
  
  @see com.ibm.websphere.sib.api.jms.JmsQueue#setGatherMessages(java.lang.String)