Here you can find the source of assertArgNotNull(T obj, String name)
private static <T> void assertArgNotNull(T obj, String name)
//package com.java2s; public class Main { private static <T> void assertArgNotNull(T obj, String name) { if (obj == null) { throw new IllegalArgumentException("argument " + name == null ? "" : name + " is null"); }/*from w w w.j a v a2 s. c om*/ } }