beanshell class loading issue with jBPM and ESB 4.8

[doudl]

While trying to run a jPDL process that uses a beanshell script I receive the following error (JBoss 5.1, ESB 4.8 and Java 6):

org.jbpm.JbpmException: couldn't get value for file 'classes/java/lang/bsh.class'

Is beanshell not included with the version of jBPM that is integrated with ESB 4.8? 

Thanks in advance,
Leon