NullPointerException in BoundaryEventHandler

Issue

We are migrating our jBPM application from BPMS 6.4.9 to RHPAM 7.1. In the new environment, we are getting below error while processes are getting loaded:

18:54:28,250 ERROR [stderr] (ServerService Thread Pool -- 76) java.lang.NullPointerException
18:54:28,250 ERROR [stderr] (ServerService Thread Pool -- 76)   at org.jbpm.bpmn2.xml.BoundaryEventHandler.end(BoundaryEventHandler.java:68)
18:54:28,251 ERROR [stderr] (ServerService Thread Pool -- 76)   at org.drools.core.xml.ExtensibleXmlParser.endElement(ExtensibleXmlParser.java:443)
18:54:28,251 ERROR [stderr] (ServerService Thread Pool -- 76)   at org.apache.xerces.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:598)
18:54:28,251 ERROR [stderr] (ServerService Thread Pool -- 76)   at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanEndElement(XMLNSDocumentScannerImpl.java:673)
18:54:28,251 ERROR [stderr] (ServerService Thread Pool -- 76)   at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(XMLDocumentFragmentScannerImpl.java:1645)