I've configured multiple branch sources (different repositories) in multibranch pipeline:

And in jenkinsfile I want to checkout all this repositories, I've tried next script:
node {
stage("Checkout") {
checkout scm
}
}
But this script checkouts only first repository. How I can checkout all repositories in one step?
I know I can list all repositories by listing in jenkinsfile itself, but I want to use already provided branch sources.