code: private boolean isDuplicateId(String componentId) {
          boolean result = false;
          if (parentTag != null) {
  
              if (parentTag.isNestedInIterator) {
                  return true;
              }
              List childComponents = parentTag.createdComponents;
              // PENDING: Need to analyze the impact of this look up on pages
              // with several levels of nesting.
              if (childComponents != null) {
                  result = childComponents.contains(componentId);
                  if (result && (!isNestedInIterator)) {
                      return true;
                  }
              }
          }
  
          return result;
      }
docs: Returns true if a component already exists with the same
  <code>id</code>. This will be the case if this tag is
  nested within <code><c:forEach></code> tag or any other JSTL loop tag
  or if the page has components with the same <code>Id</code>.
  
  @param componentId <code>id</code> to be looked up for possible
  duplication.
  @return true if this nested with <code>facesJspId</code> is duplicate.