Here you can find the source of isCollection(Class fieldClass)
public static <U> boolean isCollection(Class<U> fieldClass)
//package com.java2s; //License from project: Open Source License import java.util.Collection; public class Main { public static <U> boolean isCollection(Class<U> fieldClass) { return Collection.class.isAssignableFrom(fieldClass); }//from w w w . j a v a 2 s . c om }