private ReadableStreamChannel sendRequestGetResponse(RestRequest restRequest, RestResponseChannel restResponseChannel)
      throws Exception {
    FutureResult<ReadableStreamChannel> future = new FutureResult<>();
    handler.handle(restRequest, restResponseChannel, future::done);
    try {
      return future.get(1, TimeUnit.SECONDS);
    } catch (ExecutionException e) {
      throw e.getCause() instanceof Exception ? (Exception) e.getCause() : new Exception(e.getCause());
    }
  }
Sends the given {@link RestRequest} to the {@link GetAccountsHandler} and waits for the response and returns it.
@param restRequest the {@link RestRequest} to send.
@param restResponseChannel the {@link RestResponseChannel} where headers will be set.
@return the response body as a {@link ReadableStreamChannel}.
@throws Exception
ambry-frontend/src/test/java/com/github/ambry/frontend/PostAccountContainersHandlerTest.java