ContentAssistContext context, ICompletionProposalAcceptor acceptor) {
// TODO content assist returns "{"
if (model instanceof CustomFieldOption) {
// TODO check if this is the same as sourceOf
CustomFieldOption option = (CustomFieldOption) model;
IndexedElement e = options.sourceOfLastFieldIn(option);
if (e == null) {
e = options.rootSourceOf(option);
}
if (e instanceof MessageField) {
proposeFieldValue((MessageField) e, context, acceptor);