code: private void popAndResetToOldLevel() {
          this.levelStack.pop();
          if (!this.levelStack.isEmpty()) {
              JsonLevel newTop = levelStack.peek();
              if (newTop != null) {
                  newTop.removeLastTokenFromJsonPointer();
              }
          }
      }
docs: Helper method to clean up after being done with the last stack
  so it removes the tokens that pointed to that object.