list of all files in project-eclipse

Question

I am devloping a plug-in for eclipse that present metrics of Xtext-project.

I should present at in two levels : Xtext file and the all project.

in order to get details about the file I am using the following code in order to extract the Xtext file :

IWorkbenchPage page = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage();
IEditorPart activeEditor = page.getActiveEditor();
if (activeEditor instanceof XtextEditor) {
    XtextEditor xtextEditor = (XtextEditor) activeEditor;
    xtextEditor.getDocument().readOnly((XtextResource resource) -> {    
     ResourceHandler.resource = resource;
      });

and It works good on the current open Xtext file.

Now I want to get all the Xtext files in current eclipse project.

I tried the following code,but it doesnt seem to work :

IWorkbench workbench = PlatformUI.getWorkbench();
IWorkbenchWindow[] windows = workbench.getWorkbenchWindows();
for (IWorkbenchWindow window : windows) {
  IWorkbenchPage[] pages = window.getPages();
  for (IWorkbenchPage page : pages) {
    IEditorPart activeEditor = page.getActiveEditor();
    if (activeEditor instanceof XtextEditor) {
      XtextEditor xtextEditor = (XtextEditor) activeEditor;
      xtextEditor.getDocument().readOnly((XtextResource resource) -> {
        resourceList.add(resource);

the best solution for me is getting a list of XtextResource.

thanks.