@SuppressWarnings({"HardCodedStringLiteral"})
  private static Document createDelta(@Nullable Element oldRoot, Element newRoot) {
    ourFileToProblem = new HashMap<>();
    List newProblems = newRoot.getChildren("problem");
    for (final Object o : newProblems) {
      Element newProblem = (Element)o;
      addProblem(newProblem);
    }

    if (oldRoot != null) {
      for (final Element oldProblem : oldRoot.getChildren("problem")) {
        if (!removeIfEquals(oldProblem)) {
          addProblem(oldProblem);
        }
      }
    }

    Element root = new Element(GlobalInspectionContextBase.PROBLEMS_TAG_NAME);
    Document delta = new Document(root);

    for (ArrayList<Element> fileList : ourFileToProblem.values()) {
      if (fileList != null) {
        for (Element element : fileList) {
          root.addContent(element.clone());
        }
      }
    }

    return delta;
  }
@SuppressWarnings({"HardCodedStringLiteral"})
  private static Document createDelta(@Nullable Element oldRoot, Element newRoot)