code: public void registerMapping(String mappingName, String attributeKey, String alias) {
  		XAttributeNameMapImpl mapping = (XAttributeNameMapImpl)getMapping(mappingName);
  		mapping.registerMapping(attributeKey, alias);
  	}
docs: Registers a known attribute for mapping in a given attribute name
  map. <b>IMPORTANT:</b> This method should only be called when one
  intends to create, or add to, the global attribute name mapping.
  
  @param mappingName Name of the mapping to register with.
  @param attributeKey Attribute key to be mapped.
  @param alias Alias to map the given attribute to.