similar to JENKINS-50393 but as a global declarative shared library

I have a pipelines-lib/vars/basicDeclarative.groovy file with contents like:

def call(body) {
    def config = [:]
    body.resolveStrategy = Closure.DELEGATE_FIRST
    body.delegate = config
    body()
    pipeline {
        ...
        stages {
            stage("Checkout") {
                steps {
                    checkout perforce(
                        ...
                        workspace: manualSpec(
                            ...
                            name: 'jenkins-${JOB_NAME}',
                            ...
                            spec: clientSpec(
                                view: config.p4view
                                ...
                            )
                        ...
                        )
                    ...
                    )
               }
           }
       }
   }
}

that when called with a Jenkinsfile script like:

#!groovy
@Library('pipelines-lib') _
basicDeclarative {
    p4view = """\
    //depot/foo/bar/... //jenkins-${JOB_NAME}/...
    """
}

results in errors like:

... p4 client -o jenkins-pipelines-lib-test +
... p4 client -i +
P4: Unable to setup workspace: com.perforce.p4java.exception.RequestException: Error in client specification.
Mapping '//jenkins-null/...' is not under '//jenkins-pipelines-lib-test/...'.

note the workspace name is expanded properly but the view mapping is not

–

many edits to try and fix formatting - preformatted/monospace does not work well with curly braces