DataflowPipelineRunner: preparation for 1.8.1 release

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=141532913

sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/DataflowPipelineRunner.java

@@ -216,14 +216,14 @@ public class DataflowPipelineRunner extends PipelineRunner<DataflowPipelineJob>
   private DataflowPipelineRunnerHooks hooks;
 
   // Environment version information.
-  private static final String ENVIRONMENT_MAJOR_VERSION = "5";
+  private static final String ENVIRONMENT_MAJOR_VERSION = "6";
 
   // Default Docker container images that execute Dataflow worker harness, residing in Google
   // Container Registry, separately for Batch and Streaming.
   public static final String BATCH_WORKER_HARNESS_CONTAINER_IMAGE
-      = "dataflow.gcr.io/v1beta3/java-batch:1.8.0";
+      = "dataflow.gcr.io/v1beta3/java-batch:1.8.1";
   public static final String STREAMING_WORKER_HARNESS_CONTAINER_IMAGE
-      = "dataflow.gcr.io/v1beta3/java-streaming:1.8.0";
+      = "dataflow.gcr.io/v1beta3/java-streaming:1.8.1";
 
   // The limit of CreateJob request size.
   private static final int CREATE_JOB_REQUEST_LIMIT_BYTES = 10 * 1024 * 1024;