Getting an Exception org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId in EAP 6

Issue

• JBoss EAP stopped abnormally, We're getting the below error:

org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId:
17:51:04,792 ERROR [org.jboss.msc.service.fail] (ServerService Thread Pool -- 18) MSC000001: Failed to start service jboss.persistenceunit."test.ear/test-web.war#Test": org.jboss.msc.service.StartException in service jboss.persistenceunit."test.ear/test-web.war#Test": org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId:
    at org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1.run(PersistenceUnitServiceImpl.java:103)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_71]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_71]
    at java.lang.Thread.run(Thread.java:745) [rt.jar:1.7.0_71]
    at org.jboss.threads.JBossThread.run(JBossThread.java:122) [jboss-threads-2.1.2.Final-redhat-1.jar:2.1.2.Final-redhat-1]
Caused by: org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId:
    at org.hibernate.cfg.CopyIdentifierComponentSecondPass.doSecondPass(CopyIdentifierComponentSecondPass.java:100)
    at org.hibernate.cfg.Configuration.processSecondPassesOfType(Configuration.java:1434)
    at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1390)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1786)
    at org.hibernate.ejb.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:96)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:915)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:900)
    at org.hibernate.ejb.HibernatePersistence.createContainerEntityManagerFactory(HibernatePersistence.java:76)
    at org.jboss.as.jpa.service.PersistenceUnitServiceImpl.createContainerEntityManagerFactory(PersistenceUnitServiceImpl.java:200)
    at org.jboss.as.jpa.service.PersistenceUnitServiceImpl.access$600(PersistenceUnitServiceImpl.java:57)
    at org.jboss.as.jpa.service.PersistenceUnitServiceImpl$1.run(PersistenceUnitServiceImpl.java:99)
    ... 4 more

17:51:04,798 ERROR [org.jboss.as.controller.management-operation] (DeploymentScanner-threads - 2) JBAS014612: Operation ("deploy") failed - address: ([("deployment" => test.ear")]) - failure description: {"JBAS014671: Failed services" => {"jboss.persistenceunit.\"test.ear/test.war#Test\"" => "org.jboss.msc.service.StartException in service jboss.persistenceunit.\"test.ear/test.war#Test\": org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId:

    Caused by: org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId: "}}
17:51:04,800 ERROR [org.jboss.as.server] (DeploymentScanner-threads - 2) JBAS015870: Deploy of deployment "test.ear" was rolled back with the following failure message: 
{"JBAS014671: Failed services" => {"jboss.persistenceunit.\"test.ear/test-web.war#Test\"" => "org.jboss.msc.service.StartException in service jboss.persistenceunit.\"test.ear/test-web.war#Test\": org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId:

    Caused by: org.hibernate.AssertionFailure: Unexpected nested component on the referenced entity when mapping a @MapsId: "}}