org.activiti.engine.ActivitiOptimisticLockingException: HistoricVariableInstanceEntity[id=e7a3dcba-d72b-11e6-873a-1c1b0d35981e, name=userId, revision=1, type=string, textValue=王] was updated by another transaction concurrently
at org.activiti.engine.impl.db.DbSqlSession.flushUpdates(DbSqlSession.java:872)
at org.activiti.engine.impl.db.DbSqlSession.flush(DbSqlSession.java:611)
at org.activiti.engine.impl.interceptor.CommandContext.flushSessions(CommandContext.java:211)
at org.activiti.engine.impl.interceptor.CommandContext.close(CommandContext.java:137)
at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:66)
at org.activiti.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:47)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:133)
at org.activiti.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:45)
at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:31)
at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:40)
at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:35)
执行审批后，报这个错误
