code: private long getJobExecutionIdFromExecutingSubWorkUnitKey(String comparisonKey) {
          try {
              return Long.parseLong(comparisonKey.split("::")[0]);
          } catch (NumberFormatException e) {
              throw new IllegalStateException("Sub Work Unit found without a parent Execution Id");
          }
      }
docs: /*
  Gets a jobExecutionId from the SubWorkUnitComparisonHelper comparisonKey
  If subWorkUnit is a step, key format is "jobExecutionId:StepName:PartitionNumber"
  If subWorkUnit is a split-flow, key format is "jobExecutionId:flowName"
  
  @param the key used in executingSubWorkUnits.
  
  @return jobExecutionId