jBPM process failing with JbpmException in SOA-P 4.3 CP02

Issue

We recently migrated to SOA-P 4.3 CP02 from a previous version. We are using jBPM to orchestrate our ESB services.

The processdefinitions which have been executed without errors in earlier SOA-P versions now fail with the following exception:

WARN  [org.jbpm.graph.action.Script] exception during evaluation of script expression
org.jbpm.JbpmException: couldn't get value for file 'classes/java/lang/bsh.class'
        at org.jbpm.file.def.FileDefinition.getBytes(FileDefinition.java:196)
        at org.jbpm.instantiation.ProcessClassLoader.findClass(ProcessClassLoader.java:137)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
        at java.lang.Class.forName0(Native Method)
...
Caused by: java.lang.NullPointerException
        at org.jbpm.file.def.FileDefinition.getBytesFromDb(FileDefinition.java:213)
        at org.jbpm.file.def.FileDefinition.getBytes(FileDefinition.java:193)
        ... 71 more