content: /*
   * Copyright (C) 2020 ActiveJ LLC.
   *
   * Licensed 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
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * 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.
   */
  
  package io.activej.promise;
  
  import org.jetbrains.annotations.Nullable;
  
  /**
   * Represents a {@link CompletePromise} with result that equals {@code null}.
   * Optimized for multiple reuse since its result never changes.
   */
  public final class CompleteNullPromise<T> extends CompletePromise<T> {
  	static final CompleteNullPromise<?> INSTANCE = new CompleteNullPromise<>();
  
  	@SuppressWarnings("unchecked")
  	static <T> CompleteNullPromise<T> instance() {
  		return (CompleteNullPromise<T>) INSTANCE;
  	}
  
  	private CompleteNullPromise() {}
  
  	@Override
  	public @Nullable T getResult() {
  		return null;
  	}
  }
  