How to observe a file drop event

IntelliJ Platform
1

I have read the documentation: Listeners | IntelliJ Platform Plugin SDK

I have added the message subscription code to my StartupActivity.

    project.getMessageBus().connect().subscribe(VirtualFileManager.VFS_CHANGES,
            new BulkFileListener() {
                @Override
                public void after(@NotNull List<? extends VFileEvent> events) {
                    // handle the events
                    System.out.println("MyFileDropListener.after: "+events);
                }
            });

I have registered my listener in plugin.xml

<applicationListeners>
    <listener class="simula.plugin.util.MyVfsListener"
              topic="com.intellij.openapi.vfs.newvfs.BulkFileListener"/>
</applicationListeners>

And implemented MyVfsListener.java

public class MyVfsListener implements BulkFileListener {
      @Override
      public void after(@NotNull List<? extends VFileEvent> events) {
            System.out.println("MyVfsListener.after: "+events);
      }
}

When I run my plugin and drop a file, no ‘after’ method is called.
However; the editor got the file and showed it correctly.

What am I doing wrong ?

2

In order to handle file drop events please use com.intellij.openapi.editor.FileDropHandler extensions.

interface FileDropHandler {
  /**
   * @return true, if the event is handled and must not be propagated further to the rest of handlers
   */
  suspend fun handleDrop(e: FileDropEvent): Boolean
}

See com.intellij.htmltools.ide.HtmlFileDropHandler as an example.

<fileDropHandler implementation="com.intellij.htmltools.ide.HtmlFileDropHandler"/>
3

Where do I find it ?

4

Where do I find: com.intellij.htmltools.ide.HtmlFileDropHandler as an example.

5

It is part of IntelliJ IDEA Sources