in tools/javac/ApiCollector.java [234:241]
private Set<Modifier> getModifiers(Element e) {
Set<Modifier> set = e.getModifiers();
if (!ALLOWED_MODIFIERS.containsAll(set)) {
processingEnv.getMessager().printMessage(Diagnostic.Kind.ERROR,
"Only some modifiers are allowed in public API: " + ALLOWED_MODIFIERS, e);
}
return set;
}