docs: public static boolean applyEditSet(Element plfChild, Element original) {
          // first get edit set if it exists
          Element editSet = null;
          try {
              editSet = getEditSet(plfChild, null, null, false);
          } catch (Exception e) {
              // should never occur unless problem during create in getEditSet
              // and we are telling it not to create.
              return false;
          }
  
          if (editSet == null || editSet.getChildNodes().getLength() == 0) return false;
  
          if (original.getAttribute(Constants.ATT_EDIT_ALLOWED).equals("false")) {
              // can't change anymore so discard changes
              plfChild.removeChild(editSet);
              return false;
          }
  
          Document ilf = original.getOwnerDocument();
          boolean attributeChanged = false;
          Element edit = (Element) editSet.getFirstChild();
  
          while (edit != null) {
              String attribName = edit.getAttribute(Constants.ATT_NAME);
              Attr attr = plfChild.getAttributeNode(attribName);
  
              // preferences are only updated at preference storage time so
              // if a preference change exists in the edit set assume it is
              // still valid so that the node being edited will persist in
              // the PLF.
              if (edit.getNodeName().equals(Constants.ELM_PREF)) attributeChanged = true;
              else if (attr == null) {
                  // attribute removed. See if needs removing in original.
                  attr = original.getAttributeNode(attribName);
                  if (attr == null) // edit irrelevant,
                  editSet.removeChild(edit);
                  else {
                      // edit differs, apply to original
                      original.removeAttribute(attribName);
                      attributeChanged = true;
                  }
              } else {
                  // attribute there, see if original is also there
                  Attr origAttr = original.getAttributeNode(attribName);
                  if (origAttr == null) {
                      // original attribute isn't defined so need to add
                      origAttr = (Attr) ilf.importNode(attr, true);
                      original.setAttributeNode(origAttr);
                      attributeChanged = true;
                  } else {
                      // original attrib found, see if different
                      if (attr.getValue().equals(origAttr.getValue())) {
                          // they are the same, edit irrelevant
                          editSet.removeChild(edit);
                      } else {
                          // edit differs, apply to original
                          origAttr.setValue(attr.getValue());
                          attributeChanged = true;
                      }
                  }
              }
              edit = (Element) edit.getNextSibling();
          }
          return attributeChanged;
      }