Groovy Pipeline execution - Variables are mandatory?

Summary:

Using a Groovy BR to trigger a pipeline (export mapping job) and it was working fine with no variables defined. When the rule was triggered today interestingly Pipeline Parent/Child jobs did not appear in the process details of DM and BR completes successfully! Once I put in some variables and upon re-execution the groovy BR now picks up Parent/Child jobs as expected. ARE VARIABLES MANDATORY PARAM FOR A PIPELINE EXECUTIONS NOW??? PS: tried multiple times without variables and each time the BR completed with no issues but no effect on any jobs of the pipeline that it should have run