Don't use String8::empty am: fed7d54dfc am: 8be4b41fd7 am: 396ccf817c am: 9d84d994af

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2707753

Change-Id: I2b7cf818bec1823394b8fb44a7b98edde81092a6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>