//set name of the model (root element)
((Model) xtextResource.getContents().get(0)).setName("defaultModelName");

public class MyLinker extends Linker {

	@Inject
	private CdalfGrammarAccess grammarAccess;
        @Override
	public void ensureLinked(EObject obj, IDiagnosticProducer producer) {
		super.ensureLinked(obj, producer); 
		if (obj instanceof SomeElements) {
			SomeElementsasso = (SomeElements) obj;
			// set default attributes
			
			
		}
	}