gradle - Eclipse / LibGDX can't load Tools extension -> Particle Effects -

I am trying to add the LibGDX "Tools" extension to an existing project to use a particle emitter, but It does not seem to work.

I had initially constructed the particle emitter I am trying to use in any other workspace, but I have copied the particle emitter file to the property folder of this current project and I The copy that was working in another project when I run the second project, it runs fine, but in this I get the following error:

  Exceptions in the thread "LWJGL application C "com.badlogic.gdx.utils.GdxRuntimeException: According to the document, I have added the following line to the build.grade file in the root of my workspace:  
  compilation" com .badlogicgames.gdx: gdx-tools: $ gdx version " 
 
 The documentation says that I have to" gradually refresh the dependency "but there is no substitute for doing so in eclipse (I'm using version 3.8.1 if that helps). 
 
 So I think my main question is how do I refresh the grade dependency? I've read a post somewhere, who said that you right-click on the project and chose "Refresh Dependency" from the Gradle menu, but in the right-click menu (or anywhere, as far as I can tell) There is no grader menu. While pinging around the menu in the Eclipse, I got an option to "convert to Gradal Project". I / P> 

What was said in someone's first comment Based on this, I tried on a journey that gave me a "grade" menu in the right-click menu, so I chose "refresh all" from the Gradle menu and now it works :)