[FLINK-11460] [test] Remove the useless class AcknowledgeStreamMockEnvironment

This closes #7611.

flink-streaming-java/src/test/java/org/apache/flink/streaming/runtime/tasks/AcknowledgeStreamMockEnvironment.java

-/*
- * 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
- *
- * 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 org.apache.flink.streaming.runtime.tasks;
-
-import org.apache.flink.api.common.ExecutionConfig;
-import org.apache.flink.configuration.Configuration;
-import org.apache.flink.core.testutils.OneShotLatch;
-import org.apache.flink.runtime.checkpoint.CheckpointMetrics;
-import org.apache.flink.runtime.checkpoint.TaskStateSnapshot;
-import org.apache.flink.runtime.operators.testutils.MockInputSplitProvider;
-import org.apache.flink.runtime.state.TaskStateManager;
-
-/**
- * Stream environment that allows to wait for checkpoint acknowledgement.
- */
-public class AcknowledgeStreamMockEnvironment extends StreamMockEnvironment {
-	private final OneShotLatch checkpointLatch = new OneShotLatch();
-	private volatile long checkpointId;
-	private volatile TaskStateSnapshot checkpointStateHandles;
-
-	public AcknowledgeStreamMockEnvironment(
-		Configuration jobConfig,
-		Configuration taskConfig,
-		ExecutionConfig executionConfig,
-		long memorySize,
-		MockInputSplitProvider inputSplitProvider,
-		int bufferSize,
-		TaskStateManager taskStateManager) {
-		super(
-			jobConfig,
-			taskConfig,
-			executionConfig,
-			memorySize,
-			inputSplitProvider,
-			bufferSize,
-			taskStateManager);
-	}
-
-	public long getCheckpointId() {
-		return checkpointId;
-	}
-
-	@Override
-	public void acknowledgeCheckpoint(
-		long checkpointId,
-		CheckpointMetrics checkpointMetrics,
-		TaskStateSnapshot checkpointStateHandles) {
-
-		this.checkpointId = checkpointId;
-		this.checkpointStateHandles = checkpointStateHandles;
-		checkpointLatch.trigger();
-	}
-
-	public OneShotLatch getCheckpointLatch() {
-		return checkpointLatch;
-	}
-
-	public TaskStateSnapshot getCheckpointStateHandles() {
-		return checkpointStateHandles;
-	}
-}