Summary
When using the Directive Generator, building a when / allOf directive with no conditions attached produces a NPE. This was another accidental find.

Steps to recreate
1. Go to the Declarative Directive Generator via http://1.2.3.4:8080/job/your-pipeline-job/directive-generator/

2. Set it up as follows:

• Sample Directive: when
• whenCondition: allOf
• Execute the stage if all nested conditions are true: no selections made

3. And press the Generate Declarative Directive button, you'll get a NPE in your sample:

when {
  // ERROR TRANSLATING CONDITIONAL: java.lang.NullPointerException
}

Accidental find.