After upgrading to byteman version 4.0.9 I found that if a script contains more than one rule the rule checker fails with a null pointer:

[ERROR] Failed to execute goal org.jboss.byteman:byteman-rulecheck-maven-plugin:4.0.9:rulecheck (rulecheck) on project arjuna: Execution rulecheck of goal org.jboss.byteman:byteman-rulecheck-maven-plugin:4.0.9:r
ulecheck failed.: NullPointerException -> [Help 1]
[ERROR]

An example reproducer is when we build the artefact org.jboss.narayana.arjunacore:arjuna:5.10.1.Final-SNAPSHOT

The byteman upgrade was introduced by pull request 1530 (https://github.com/jbosstm/narayana/pull/1530)

The issue occurs whenever a byteman script contains more that one rule (so the workaround is to only have single rule scripts).