...
annotations += model.toAnnotation("org.my.MyAnnotation")
...

...
annotations += model.toAnnotation("org.my.MyAnnotation", "MyValue")
...

public class ExtendedJvmTypesBuilder extends JvmTypesBuilder {
	
	@Inject
	private TypeReferences references;
	
	@Inject
	private TypesFactory typesFactory;
	
	@Nullable
	public JvmAnnotationReference toAnnotationExtended(@Nullable EObject sourceElement, @Nullable String annotationTypeName,
			Pair<String, String> ...  values) {
		JvmAnnotationReference result = typesFactory.createJvmAnnotationReference();
		JvmType jvmType = references.findDeclaredType(annotationTypeName, sourceElement);
		if (jvmType == null) {
			throw new IllegalArgumentException("The type "+annotationTypeName +" is not on the classpath.");
		}
		if (!(jvmType instanceof JvmAnnotationType)) {
			throw new IllegalArgumentException("The given class " + annotationTypeName + " is not an annotation type.");
		}
		JvmAnnotationType annotationType = (JvmAnnotationType) jvmType;
		result.setAnnotation(annotationType);
		
		for (Pair<String, String> value : values) {
			JvmStringAnnotationValue annotationValue = typesFactory.createJvmStringAnnotationValue();
			annotationValue.getValues().add(value.getValue());
			JvmOperation operation = getJvmOperation(annotationType, value.getKey());
			if (operation != null) {				
				annotationValue.setOperation(operation);
			}
			result.getValues().add(annotationValue);
		}
	
		return result;
	}
	
	private JvmOperation getJvmOperation(JvmAnnotationType type, String name) {
		for (JvmOperation op : type.getDeclaredOperations()) {
			if (op.getSimpleName().equals(name)) {
				return op;
			}
		}
		return null;
	}


}

JvmAnnotationReferenceImplCustom 

JvmAnnotationReference result = typesFactory.createJvmAnnotationReference();

@Override
	public EList<JvmAnnotationValue> getValues() {
		EList<JvmAnnotationValue> explicitValues = getExplicitValues();
		List<JvmOperation> operations = Lists.newArrayList(getAnnotation().getDeclaredOperations());
		if (operations.size() <= explicitValues.size()) {
			return ECollections.unmodifiableEList(explicitValues);
		}
		Set<JvmOperation> seenOperations = Sets.newHashSetWithExpectedSize(operations.size());
		BasicEList<JvmAnnotationValue> result = new BasicEList<JvmAnnotationValue>(operations.size());
		for(JvmAnnotationValue value: explicitValues) {
			seenOperations.add(value.getOperation());
			result.add(value);
		}
		for(JvmOperation operation: operations) {
			if (seenOperations.add(operation)) {
				JvmAnnotationValue defaultValue = operation.getDefaultValue();
				if (defaultValue != null) {
					result.add(defaultValue);
				}
			}
		}
		return ECollections.unmodifiableEList(result);
	}

public enum MyColors {
   red,
   green,
   blue;
}

public interface MyFeatures {
   public static final String MY_COLOR_FEATURE = "myColorFeature";
}

public class Something {
   @MyAnnotation(feature=Test.MY_COLOR_FEATURE, color=MyColors.green)
   public void someMethod() {}
}

JvmAnnotationReferenceImplCustom>>getValues()

		(...)
		for(JvmOperation operation: operations) {
			if (seenOperations.add(operation)) {
				JvmAnnotationValue defaultValue = operation.getDefaultValue();
				if (defaultValue != null) {
					result.add(defaultValue);
				}
			}
		}
		return ECollections.unmodifiableEList(result);