Auto-format on save

public class MyDslDocumentProvider extends XtextDocumentProvider {
	@Override
	protected void doSaveDocument(IProgressMonitor monitor, Object element, IDocument document, boolean overwrite)
			throws CoreException {
		try {
		  final IHandlerService service = (IHandlerService) PlatformUI.getWorkbench().getService(IHandlerService.class);
			service.executeCommand("org.eclipse.xtext.ui.FormatAction", null);
		} catch (Exception e) {
			e.printStackTrace();
		}
		super.doSaveDocument(monitor, element, document, overwrite);
	}
}

// Add binding in the DSL UI Module
def Class<? extends XtextDocumentProvider> bindXtextDocumentProvider() { return MyDslDocumentProvider }

// Courtesy: http://stackoverflow.com/questions/31116928/auto-pretty-formatting-in-xtext