Google Maps SDK for Android Rx extension

GoogleMaps+Rx.kt

import android.content.Context
import com.google.android.gms.maps.GoogleMap
import com.google.android.gms.maps.SupportMapFragment
import io.reactivex.Observable
import io.reactivex.Single
import io.reactivex.disposables.Disposables

@androidx.annotation.CheckResult
fun SupportMapFragment.map(): Single<GoogleMap> =
        Single.create { emitter ->
            this.getMapAsync { googleMap ->
                if (googleMap != null) {
                    emitter.onSuccess(googleMap)
                } else {
                    emitter.onError(NullPointerException("Could not obtain GoogleMap"))
                }
            }
        }

@androidx.annotation.CheckResult
fun GoogleMap.cameraMoveStarted(): Observable<Int> =
        Observable.create { emitter ->
            setOnCameraMoveStartedListener {
                emitter.onNext(it)
            }
        }

@androidx.annotation.CheckResult
fun GoogleMap.cameraIdle(): Observable<Unit> =
        Observable.create { emitter ->
            setOnCameraIdleListener {
                emitter.onNext(Unit)
            }
        }

@androidx.annotation.CheckResult
fun GoogleMap.myLocationButtonClicks(): Observable<Unit> =
        Observable.create { emitter ->
            setOnMyLocationButtonClickListener {
                emitter.onNext(Unit)
                false
            }
            emitter.setDisposable(Disposables.fromRunnable {
                setOnMyLocationButtonClickListener(null)
            })
        }