Nested stages inside parallel in declarative pipeline not supported

[jwalter]

Trying to run the following declarative pipeline with "runScript":

pipeline {
    stages {
        stage('Parallel Stage') {
            parallel {
                stage('Branch A') {
                    stages {
                        stage('Nested 1') {
                            steps {
                                echo "In stage Nested 1 within Branch A"
                            }
                        }
                    }
                }
            }
        }
    }
}

fails with the error message:

No signature of method: com.lesfurets.jenkins.unit.declarative.StageDeclaration.stages() is applicable for argument types: (Jenkinsfile$_run_closure1$_closure2$_closure3$_closure4$_closure5$_closure6) values: [Jenkinsfile$_run_closure1$_closure2$_closure3$_closure4$_closure5$_closure6@477ed37d]

[Willem1987]

@jwalter Could you check if the problem still exists in 1.8? A test was added for this case and it seems to work.