code: public PortalJobStatusChanged getStatusChange(Sender sender) {
          JobStatusResponse<XMLPortalSignatureJobStatusChangeResponse> statusChangeResponse = client.getPortalStatusChange(Optional.ofNullable(sender));
          if (statusChangeResponse.gotStatusChange()) {
              return JaxbEntityMapping.fromJaxb(statusChangeResponse);
          } else {
              return noUpdatedStatus(statusChangeResponse.getNextPermittedPollTime());
          }
      }
docs: If there is a job with an updated {@link PortalJobStatus status}, the returned object contains
  necessary information to act on the status change. The returned object can be queried using
  {@link PortalJobStatusChanged#is(PortalJobStatus) .is(}{@link PortalJobStatus#NO_CHANGES NO_CHANGES)}
  to determine if there has been a status change. When processing of the status change is complete, (e.g. retrieving
  {@link #getPAdES(PAdESReference) PAdES} and/or {@link #getXAdES(XAdESReference) XAdES} documents for a
  {@link PortalJobStatus#COMPLETED_SUCCESSFULLY completed} job where all signers have {@link SignatureStatus signed} their documents),
  the returned status must be {@link #confirm(PortalJobStatusChanged) confirmed}.
  
  @return the changed status for a job, or an instance indicating {@link PortalJobStatus#NO_CHANGES no changes},
  never {@code null}.