private static DocumentEx createSpecialDocument() {
    DocumentEx doc = new DocumentImpl("", false, false); // restrict "\r\n" line separators
    doc.putUserData(FileDocumentManagerImpl.NOT_RELOADABLE_DOCUMENT_KEY,
                    new Object());  // to protect document from illegal content changes (see usages of the key)
    UndoUtil.disableUndoFor(doc); // disabling Undo-functionality, provided by IDEA
    return doc;
  }
private static DocumentEx createSpecialDocument()