mbed-os/tools/test/config/override_labels_libs/lib1/mbed_lib.json

{
    "name": "lib1",
    "config": {
        "p1": "v_p1_lib1",
        "p2": "v_p2_lib1",
        "p3": "v_p3_lib1"
    },
    "target_overrides": {
        "b1_label": {
            "p1": "v_p1_lib1[b1_label]"
        },
        "b2_label": {
            "p2": "v_p2_lib1[b2_label]"
        }
    }
}