public class GenerationHandler extends AbstractHandler implements IHandler {
    
    @Inject
    private IGenerator generator;
 
    @Inject
    private Provider<EclipseResourceFileSystemAccess2> fileAccessProvider;
     
    @Inject
    IResourceDescriptions resourceDescriptions;
     
    @Inject
    IResourceSetProvider resourceSetProvider;
     
    @Override
    public Object execute(ExecutionEvent event) throws ExecutionException {
        ISelection selection = HandlerUtil.getCurrentSelection(event);
        if (selection instanceof IStructuredSelection) {
            IStructuredSelection structuredSelection = (IStructuredSelection) selection;
            Object firstElement = structuredSelection.getFirstElement();
            
            if (firstElement instanceof IFile) {
                IFile file = (IFile) firstElement;
                IProject project = file.getProject();
                IFolder srcGenFolder = project.getFolder("src-gen");
                
                if (!srcGenFolder.exists()) {
                    try {
                        srcGenFolder.create(true, true,
                                new NullProgressMonitor());
                    } catch (CoreException e) {
                        return null;
                    }
                }
 
                final EclipseResourceFileSystemAccess2 fsa = fileAccessProvider.get();
                fsa.setOutputPath(srcGenFolder.getFullPath().toString());
                fsa.setMonitor(new NullProgressMonitor());
                fsa.setProject(project);
                 
                URI uri = URI.createPlatformResourceURI(file.getFullPath().toString(), true);
                ResourceSet rs = resourceSetProvider.get(project);
                Resource r = rs.getResource(uri, true);
                generator.doGenerate(r, fsa);
            }
        }
        return null;
    }
 
    @Override
    public boolean isEnabled() {
        return true;
    }
}