code: @Override
    public void recordTaskDefinitionKeyChange(String taskId, String taskDefinitionKey) {
      if (isHistoryLevelAtLeast(HistoryLevel.AUDIT)) {
        HistoricTaskInstanceEntity historicTaskInstance = getHistoricTaskInstanceEntityManager().findById(taskId);
        if (historicTaskInstance != null) {
          historicTaskInstance.setTaskDefinitionKey(taskDefinitionKey);
        }
      }
    }
docs: /*
  (non-Javadoc)
  
  @see org.activiti.engine.impl.history.HistoryManagerInterface# recordTaskDefinitionKeyChange (org.activiti.engine.impl.persistence.entity.TaskEntity, java.lang.String)