pkg/front_end/testcases/general/nested_lib_spec/extra_libraries.json

{
  "_vm": {
    "include": [
      {
        "path": "subfolder/sub_libraries.json",
        "target": "subtarget"
      }
    ],
    "libraries": {
      "extra": {
        "patches": [
          "extra_patch_lib.dart"
        ],
        "uri": "extra_lib.dart"
      }
    }
  }
}