code: private Object evaluateRoleExpression(ActionBean bean, String expression)
  	{
  		try
  		{
  			LOG.debug("Evaluating expression: '" + expression + '\'');
  
  			// This is somewhat of a hack until the ExpressionEvaluator becomes more accessible.
  			ParameterName name = new ParameterName("security");
  			List<Object> values = new ArrayList<Object>();
  			values.add(null);
  			ValidationMetadata metadata = new ValidationMetadata("security").expression(expression);
  			ValidationErrors errors = new ValidationErrors();
  
  			ExpressionValidator.evaluate(bean, name, values, metadata, errors);
  
  			return errors.isEmpty();
  		}
  		catch (Exception exc)
  		{
  			throw new StripesRuntimeException(exc);
  		}
  	}
docs: Evaluate the given EL expression using the current action bean to resolve variables.
  
  @param bean       the bean to evaluate the expression on
  @param expression the EL expression to evaluate
  @return the result of the EL expression