@Override
  public ResponseStatus getStatus() {
    ResponseStatus status = null;
    try {
      if (responseMetadata.has(RESPONSE_STATUS_KEY)) {
        status = ResponseStatus.valueOf(responseMetadata.getString(RESPONSE_STATUS_KEY));
      }
    } catch (Exception e) {
      throw new IllegalStateException(e);
    }
    return status;
  }
Called when an event (function call) finishes successfully in MockRestResponseChannel. Does *not* trigger if the
event (function) fails.
@param mockRestResponseChannel the {@link MockRestResponseChannel} where the event occurred.
@param event the {@link Event} that occurred.
ambry-test-utils/src/main/java/com/github/ambry/rest/MockRestResponseChannel.java