DrmConfiguration.Builder#setLicenseRequestHeaders now rejects null, since https://github.com/google/ExoPlayer/commit/8fd1381a84470813827a83921cf3dd2b8603ecb0 This private method isn't needed at all, it's extracting the headers from the item that the DrmConfiguration.Builder is already based on. PiperOrigin-RevId: 403973523
