@Override
	public String getCategory() {
		String category = record.getString(BookmarkDBAdapter.CATEGORY_COL);
		return category != null ? category : ""; // NOTE: Old data may have stored null
	}
Returns bookmark type or null if type has been removed.
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/bookmark/BookmarkDB.java