private String getInstructorString(HashMap<String, Object> map) {
		@SuppressWarnings("unchecked")
		ArrayList<Object> ids = (ArrayList<Object>) map.get("instructorIds");
		if (ids.isEmpty())
			return null;
		String result = "";
		for (Object id : ids) {
			HashMap<String, Object> ins = instructors.get(id);
			if (ins == null) {
				System.out.println("Unkown instructor id " + id);
				continue;
			}
			result += ", " + ins.get("firstName") + " " + ins.get("lastName");
		}
		return result.substring(2);
	}