how to use "CollapseExpandDocCommentsHandler"

Finally found a good code example on the web :https://www.programcreek.com/java-api-examples/?api=com.intellij.codeInsight.folding.CodeFoldingManager  

Wich gives the following code :

@Override
public void actionPerformed(@NotNull AnActionEvent prEvent)
{
  Project vProject = prEvent.getProject();
  if (vProject==null)
   return;

  Editor vEditor = prEvent.getData(CommonDataKeys.EDITOR);
  if (vEditor==null)
   return;

  CodeFoldingManager foldingManager = CodeFoldingManager.getInstance(vProject);
  foldingManager.updateFoldRegions(vEditor);

  final FoldRegion[] vFoldRegions = vEditor.getFoldingModel().getAllFoldRegions();

  Runnable vFoldProcess = new Runnable()
  {
    @Override
    public void run()
    {
      for (FoldRegion vRegion : vFoldRegions)
       {
         //PsiElement element = EditorFoldingInfo.get(vEditor).getPsiElement(vRegion);
         String vText=vRegion.getPlaceholderText();
         if (wUtils.wStrContains(vText,"_gx_"))
          {
            if ( (wUtils.wStrContains(vText,"interface")) || (wUtils.wStrContains(vText,"initialization")) )
             vRegion.setExpanded(false);
          }
        }//for
      }//run
    };

   vEditor.getFoldingModel().runBatchFoldingOperation(vFoldProcess);
}//[*]