NullPointerException caused by SetDefaultLocalBusinessInterfaceProcessor when migrating from JBoss EAP 4 to JBoss EAP 5?

Issue

• We are trying to migrate our application from JBoss EAP 4.3 to JBoss EAP 5.1.2, on startup we are getting this exception:

...
Caused by: java.lang.NullPointerException
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:247)
    at org.jboss.metadata.process.processor.ejb.jboss.SetDefaultLocalBusinessInterfaceProcessor.process(SetDefaultLocalBusinessInterfaceProcessor.java:114)
    at org.jboss.metadata.process.chain.ejb.jboss.JBossMetaDataProcessorChain.process(JBossMetaDataProcessorChain.java:115)
    at org.jboss.ejb3.deployers.Ejb3MetadataProcessingDeployer.deploy(Ejb3MetadataProcessingDeployer.java:142)
    at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:179)
    ... 30 more