code: private String checkConflict(Element elem, String oldAttrValue, String attr)
  			throws JspCoreException {
  
  		String result = oldAttrValue;
  		String attrValue = null; 
  		if (elem.getAttributeNode(attr) != null ) {
  			attrValue = elem.getAttributeNode(attr).getValue();
  		}
  		if (attrValue != null) {
  			if (oldAttrValue != null && !oldAttrValue.equals(attrValue)) {
  	            throw new JspTranslationException(
  	                    elem,
  	                    "jsp.error.tag.conflict.attr",
  	                    new Object[] { attr, oldAttrValue, attrValue });
  			}
  			result = attrValue;
  		}
  		return result;
  	}
docs: new method for jsp2.1ELwork