flowableの历史查询

1.  历史查询主要用到的方法，createProcessInstanceHistoryLogQuery包含一个流程实例的几乎所有信息。

public interface HistoryService {

    /**
     * Creates a new programmatic query to search for {@link HistoricProcessInstance}s.
     */
    HistoricProcessInstanceQuery createHistoricProcessInstanceQuery();

    /**
     * Creates a new programmatic query to search for {@link HistoricActivityInstance}s.
     */
    HistoricActivityInstanceQuery createHistoricActivityInstanceQuery();

    /**
     * Creates a new programmatic query to search for {@link HistoricTaskInstance}s.
     */
    HistoricTaskInstanceQuery createHistoricTaskInstanceQuery();

    /**
     * Creates a new programmatic query to search for {@link HistoricVariableInstance}s.
     */
    HistoricVariableInstanceQuery createHistoricVariableInstanceQuery();

    /**
     * Allows to retrieve the {@link ProcessInstanceHistoryLog} for one process instance.
     */
    ProcessInstanceHistoryLogQuery createProcessInstanceHistoryLogQuery(String processInstanceId);

}