Adding custom directories and files to Snapcraft.yaml

I have an entire directory tree that would need to be packaged up. There is 6 top level directories with subdirectories and files. I am wanting to create a Snap app out of a binary application. The main reason for this is because I don’t have the source code for a 3rd party application.

I thought I could include the directories by adding them in the “stage:” array, but I am getting errors.

parts:
  app1manual:
    # See 'snapcraft plugins'
    plugin: dump
    source: .
    stage: [app1]

apps:
  app1manual:
    command: app1
    plugs:
     - network
     - network-bind
     - system-observe
     - mount-observe
     - network-control

How could I add these directories and specify it in the snapcraft.yaml file?

To solve this every directory needs to be specified, like this:

parts:
  app1manual:
    # See 'snapcraft plugins'
    plugin: dump
    source: .
    stage: [app1, dir1, dir2, dir3, dir4]

or like this:

parts:
  app1manual:
    # See 'snapcraft plugins'
    plugin: dump
    source: .
    stage: 
    - app1
    - dir1
    - dir2
    - dir3
    - dir4