switch (desc.getKind()) {
case OPERATOR:
Declaration decl = ((OperatorDescription) desc).getDeclaration();
if (decl.getDeclaring().getName().startsWith("com.asakusafw.vocabulary.") == false) {
String elementId = context.label(
decl.toMethod(),
decl.getAnnotationType().getSimpleName(),
MessageFormat.format(
"{0}#{1}",
decl.getDeclaring().getSimpleName(),
decl.toMethod().getName()));