code: public byte[] getTaskKey(String prefix, String jobNumber, String fullId) {
      String taskComponent = fullId;
      if (fullId == null) {
        taskComponent = "";
      } else {
        String expectedPrefix = prefix + jobNumber + "_";
        if ((fullId.startsWith(expectedPrefix)) && (fullId.length() > expectedPrefix.length())) {
          taskComponent = fullId.substring(expectedPrefix.length());
        }
      }
      return taskKeyConv.toBytes(new TaskKey(this.jobKey, taskComponent));
    }
docs: Returns the Task ID or Task Attempt ID, stripped of the leading job ID, appended to the job row
  key.