Spring 4.3 SSE returns net::ERR_INCOMPLETE_CHUNKED_ENCODING 200

Question

I am using Spring mvc 4.3.30 version and Angular 11. I would like to subscribe to real time updates and it would be always unidirectional (From server to Ui) hence i opted for SSE.

Below is my code JAVA SPRING

@RestController
@RequestMapping(path = "/api/v1/cite-located-sse")
public class CiteLocatedDeltasSSEController
{


 @GetMapping(value="deltas-listener")
 public SseEmitter  citeLocatedDeltasListener() {
  SseEmitter emitter = new SseEmitter(12000L);
  ExecutorService executor = Executors.newSingleThreadExecutor();
  executor.execute(() -> {
   try {
    emitter.send("Hello!");
   } catch (Exception ex) {
    emitter.completeWithError(ex);
   }
   finally
   {
    emitter.complete();
   }
  });
  executor.shutdown();

  return emitter;
 }
}

Angular 11 Event Source Listener

@Injectable({
  providedIn: 'root'
})
export class EventSourceService{
  private baseUrl = 'cite-located-sse';


  constructor(private urlBuilder: UrlBuilder) {  }

  connect(): void {
    console.log('Connecting to SSE...');
    const url = "http://localhost:8080/api/v1/cite-located-sse/deltas-listener";
    const eventSource = new EventSource(url);
    eventSource.addEventListener('message', (event: MessageEvent) => {
       console.log('Received event: ', event)
    });
    eventSource.onerror = (error: Event) => {
        console.log('EventSource error: ', error);
        eventSource.close();
    };  
  }
}

I am using Tomcat 8.5 version, but i am receiving the below error at the client side.