source property
Specific the panorama source, can be StreetViewSource.def or StreetViewSource.outdoor.
more info see,
for android
https://developers.google.com/android/reference/com/google/android/gms/maps/model/StreetViewSource
for iOS
https://developers.google.com/maps/documentation/ios-sdk/reference/group___panorama_source
Implementation
final StreetViewSource? source;