the "version" of the processDefinition in db is a Long type not a Sting type

when I call ExecutionService.startProcessInstanceById() , I meet a Exception
"
exception while executing command org.jbpm.pvm.internal.cmd.StartProcessInstanceCmd@f9d4f7
java.lang.ClassCastException: java.lang.Long
at org.jbpm.jpdl.internal.repository.JpdlDeployer.deploy(JpdlDeployer.java:72)
"

so I debug this call process, I find the root cause of the exception is in this segment
"

String version = (String) deployment.getObjectProperty(processDefinitionName, KEY_VERSION);

"
I find in the "jbpm.repository.hbm.xml" have " <property name="longValue" column="LONGVAL_" /> " map.
I find in DeploymentProperty class the longValue is long type .
so the Long type can't cast to String