Merge pull request #27693: Make --dataflowEndpoint a public option

runners/google-cloud-dataflow-java/src/main/java/org/apache/beam/runners/dataflow/options/DataflowPipelineOptions.java

@@ -17,6 +17,7 @@
  */
 package org.apache.beam.runners.dataflow.options;
 
+import com.google.api.services.dataflow.Dataflow;
 import java.util.List;
 import java.util.Map;
 import org.apache.beam.runners.dataflow.DataflowRunner;
@@ -136,6 +137,25 @@ public interface DataflowPipelineOptions
 
   void setRegion(String region);
 
+  /**
+   * Dataflow endpoint to use.
+   *
+   * <p>Defaults to the current version of the Google Cloud Dataflow API, at the time the current
+   * SDK version was released.
+   *
+   * <p>If the string contains "://", then this is treated as a URL, otherwise {@link
+   * #getApiRootUrl()} is used as the root URL.
+   */
+  @Description(
+      "The URL for the Dataflow API. If the string contains \"://\", this"
+          + " will be treated as the entire URL, otherwise will be treated relative to apiRootUrl.")
+  @Override
+  @Default.String(Dataflow.DEFAULT_SERVICE_PATH)
+  String getDataflowEndpoint();
+
+  @Override
+  void setDataflowEndpoint(String value);
+
   /** Labels that will be applied to the billing records for this job. */
   @Description("Labels that will be applied to the billing records for this job.")
   Map<String, String> getLabels();