When using the UI to create or edit a job, the flexible publish plugin does not list 'Execute Shell' as an action, however when creating a job using DSL, 'Execute Shell' (steps->shell) is a valid action, and the resulting output does show 'Execute Shell'.

This DSL works:

freeStyleJob('thisworks') {

wrappers

{ timestamperBuildWrapper() }

steps

{ shell("ps -ef") }

publishers {
flexiblePublish {
conditionalAction {
condition

{ alwaysRun() }

runner('Run')
steps

{ shell("ps -ef") }

}
}
}

}