public void clear() {
    for (UnifiedDiffChangeUi changeUi : myPresentations) {
      changeUi.destroyHighlighter();
    }
    myPresentations.clear();

    DocumentEx document = myViewer.getEditor().getDocument();
    for (RangeMarker block : myGuardedRangeBlocks) {
      document.removeGuardedBlock(block);
    }
    myGuardedRangeBlocks.clear();

    myData = null;
    myIsContentsEqual = ThreeState.UNSURE;
  }
public void clear()