vars/customStep.groovy

def call(a, b) {
    echo "a: $a"
    echo "b: $b"
}

Pipeline:

customStep(a: "param1", b: "param2")

Jenkins executes the pipeline with "success". customStep is not executed though.

I have come to understand that I would need to define call to have a single Map parameter for this to work.

The problem is that executes this "step" without error. It simply swallows the error and merrily continues with the next steps. This makes pipelines unreliable as steps can apparently be invalid and quietly be ignored.