Here you can find the source of asSet(E... pEntities)
public static <E> Set<E> asSet(E... pEntities)
//package com.java2s; /**//from ww w.java 2s. c om * Copyright 2017 Remi Guillemette - n4dev.ca * <p> * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * <p> * http://www.apache.org/licenses/LICENSE-2.0 * <p> * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ import java.util.Collections; import java.util.HashSet; import java.util.Set; public class Main { public static <E> Set<E> asSet(E... pEntities) { if (pEntities != null) { Set<E> entities = new HashSet<>(); for (E entity : pEntities) { entities.add(entity); } return entities; } return Collections.emptySet(); } }