code: @Override
  	public Object evaluate( Message message ) throws JMSException
      {
          Boolean operandValue = operand.evaluateBoolean(message);
          if (operandValue == null)
              return null;
          
          return operandValue.booleanValue() ? Boolean.FALSE : Boolean.TRUE;
      }
docs: /*
  (non-Javadoc)
  @see net.timewalker.ffmq4.common.message.selector.expression.SelectorNode#evaluate(javax.jms.Message)