[cuebot] Complete the gRPC response in ShowInterface.SetCommentEmail (#2409)

## Related Issues
- #2408

## Summarize your change.

ManageShow.setCommentEmail called responseObserver.onNext(...) but never
responseObserver.onCompleted(), so the gRPC stream was never closed and
callers hung until they timed out (the email was still written to the
database). Every other setter in this servant closes the stream.

Add the missing onCompleted() so the RPC returns promptly, and add a
ManageShowTests.testSetCommentEmail regression test - using a recording
StreamObserver that asserts onCompleted() was called (the existing
FakeStreamObserver has empty methods and wouldn't catch this) and that
the comment email is persisted.

Fixes the hang in CueGUI's and CueWeb's Show Properties "Comment
Notification Email" field.

Author: ramonfigueiredo

cuebot/src/main/java/com/imageworks/spcue/servant/ManageShow.java

@@ -448,6 +448,7 @@ public void setCommentEmail(ShowSetCommentEmailRequest request,
         adminManager.updateShowCommentEmail(getShowEntity(request.getShow()),
                 request.getEmail().split(","));
         responseObserver.onNext(ShowSetCommentEmailResponse.newBuilder().build());
+        responseObserver.onCompleted();
     }
 
     public AdminManager getAdminManager() {

cuebot/src/test/java/com/imageworks/spcue/test/servant/ManageShowTests.java

@@ -28,10 +28,15 @@
 import com.imageworks.spcue.config.TestAppConfig;
 import com.imageworks.spcue.dao.ShowDao;
 import com.imageworks.spcue.grpc.show.Show;
+import com.imageworks.spcue.grpc.show.ShowSetCommentEmailRequest;
+import com.imageworks.spcue.grpc.show.ShowSetCommentEmailResponse;
 import com.imageworks.spcue.grpc.show.ShowSetSchedulerManagedRequest;
 import com.imageworks.spcue.grpc.show.ShowSetSchedulerManagedResponse;
 import com.imageworks.spcue.servant.ManageShow;
 
+import io.grpc.stub.StreamObserver;
+
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
@@ -47,6 +52,55 @@ public class ManageShowTests extends AbstractTransactionalJUnit4SpringContextTes
 
     private static final String SHOW_NAME = "pipe";
 
+    /**
+     * StreamObserver that records whether onNext / onCompleted were called, so a servant method
+     * that forgets to close the stream (onCompleted) is caught.
+     */
+    private static class RecordingStreamObserver<T> implements StreamObserver<T> {
+        boolean nextCalled = false;
+        boolean completed = false;
+        Throwable error = null;
+
+        @Override
+        public void onNext(T value) {
+            nextCalled = true;
+        }
+
+        @Override
+        public void onError(Throwable t) {
+            error = t;
+        }
+
+        @Override
+        public void onCompleted() {
+            completed = true;
+        }
+    }
+
+    @Test
+    @Transactional
+    @Rollback(true)
+    public void testSetCommentEmail() {
+        ShowEntity show = showDao.findShowDetail(SHOW_NAME);
+        Show showProto = Show.newBuilder().setId(show.id).setName(show.name).build();
+
+        ShowSetCommentEmailRequest request = ShowSetCommentEmailRequest.newBuilder()
+                .setShow(showProto).setEmail("first@example.com,second@example.com").build();
+        RecordingStreamObserver<ShowSetCommentEmailResponse> observer =
+                new RecordingStreamObserver<ShowSetCommentEmailResponse>();
+
+        manageShow.setCommentEmail(request, observer);
+
+        // The RPC must both emit a response and CLOSE the stream; a missing
+        // onCompleted() leaves callers hanging until they time out.
+        assertTrue(observer.nextCalled);
+        assertTrue(observer.completed);
+
+        // And the email is persisted (split on comma, matching the servant).
+        assertArrayEquals(new String[] {"first@example.com", "second@example.com"},
+                showDao.findShowDetail(SHOW_NAME).commentMail);
+    }
+
     @Test
     @Transactional
     @Rollback(true)