Here you can find the source of assertNonNull(String argumentName, Object argument)
static void assertNonNull(String argumentName, Object argument)
//package com.java2s; // Licensed under the MIT license. See LICENSE file in the project root for full license information. public class Main { static void assertNonNull(String argumentName, Object argument) { if (argument == null) throw new IllegalArgumentException("Argument '" + argumentName + "' is null."); }/* w w w . j a v a2 s. c om*/ }