code: function() {
      this.header = undefined;
      this.credentials = undefined;
      this.meta = undefined;
      this.xml = undefined;
      this.binaries = new KdbxBinaries();
      this.groups = [];
      this.deletedObjects = [];
      Object.preventExtensions(this);
  }
docs: Kdbx file (KeePass database v2)
  @constructor