code: public void checkJobIdEquality(Job expected, Job actual) {
      Preconditions.checkState(actual.getJobReference() != null
          && actual.getJobReference().getJobId() != null
          && expected.getJobReference() != null
          && expected.getJobReference().getJobId() != null
          && actual.getJobReference().getJobId().equals(expected.getJobReference().getJobId()),
          "jobIds must match in '[expected|actual].getJobReference()' (got '%s' vs '%s')",
          expected.getJobReference(), actual.getJobReference());
    }
docs: Helper to check for non-null Job.getJobReference().getJobId() and quality of the getJobId()
  between {@code expected} and {@code actual}, using Preconditions.checkState.