@Override
	protected boolean refresh(DBRecord rec) {
		if (rec == null) {
			rec = mgr.getRecord(key);
		}
		if (rec == null) {
			return false;
		}
		record = rec;
		return true;
	}
Returns bookmark type or null if type has been removed.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/bookmark/BookmarkDB.java