in src/main/java/org/apache/sling/models/annotations/apt/ValidatingAnnotationProcessor.java [101:107]
private boolean isSlingModel(Element annotatedElement) {
Element enclosingElement = annotatedElement.getEnclosingElement();
// skip any occurrence where the enclosing element is not a class or interface, should not happen
return (enclosingElement.getKind() == ElementKind.CLASS || enclosingElement.getKind() == ElementKind.INTERFACE)
&& enclosingElement.getAnnotation(Model.class) != null;
}