code: @Override
    public void recordVariableCreate(VariableInstanceEntity variable) {
      // Historic variables
      if (isHistoryLevelAtLeast(HistoryLevel.ACTIVITY)) {
       getHistoricVariableInstanceEntityManager().copyAndInsert(variable);
      }
    }
docs: /*
  (non-Javadoc)
  
  @see org.activiti.engine.impl.history.HistoryManagerInterface#recordVariableCreate (org.activiti.engine.impl.persistence.entity.VariableInstanceEntity)