Model:
	greetings+=Greeting*;
	
Greeting:
	'Hello' name=ID '!';

public class MyDslJavaValidator extends AbstractMyDslJavaValidator {

	@Check
	public void checkGreetingStartsWithCapital(Greeting greeting) {
		if (!Character.isUpperCase(greeting.getName().charAt(0))) {
			error("Name should start with a capital", MyDslPackage.Literals.GREETING__NAME);
		}
	}

}

public class Action1
	extends ActionDelegate
	implements IObjectActionDelegate {

	
	@Inject
	IResourceDescriptions resourceDescriptions;

	@Inject
	IResourceSetProvider resourceSetProvider;
	
	private ISelection selection;
	
	private IProject project;
	/**
	 * @see ActionDelegate#run(IAction)
	 */
	public void run(IAction action) {
		IFile file = (IFile) ( (IStructuredSelection) selection).getFirstElement();
		project =  file.getProject();
		String path = file.getFullPath().toString();
	
		
		URI uri = URI.createPlatformResourceURI(path, true);
		ResourceSet rs = resourceSetProvider.get(project);
		
		
		Resource r = rs.getResource(uri, true);
		
		EcoreUtil.resolveAll(r);

		if(r.getErrors().size() == 0) {
			//it always enters here if I have errors set in the JavaValidator
		}

	}

 <extension
        point="org.eclipse.ui.popupMenus">
     <objectContribution
           id="org.xtext.example.mydsl.ui.objectContribution1"
           nameFilter="*.mydsl"
           objectClass="org.eclipse.core.resources.IFile">
        <action
              class="org.xtext.example.mydsl.ui.MyDslExecutableExtensionFactory:org.xtext.example.mydsl.ui.Action1"
              enablesFor="1"
              id="org.xtext.example.mydsl.ui.action1"
              label="Test"
              menubarPath="addition"
              style="push">
        </action>
     </objectContribution>
  </extension>