[android] - add experimental pointer (#13889)

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/MapboxMap.java

@@ -228,6 +228,13 @@ public final class MapboxMap {
     }
   }
 
+  /**
+   * Experimental feature. Do not use.
+   */
+  long getNativeMapPtr() {
+    return nativeMapView.getNativePtr();
+  }
+
   // Style
 
   /**

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/maps/NativeMapView.java

@@ -70,7 +70,7 @@ final class NativeMapView implements NativeMap {
 
   // Holds the pointer to JNI NativeMapView
   @Keep
-  long nativePtr = 0;
+  private long nativePtr = 0;
 
   // Listener invoked to return a bitmap of the map
   private MapboxMap.SnapshotReadyCallback snapshotReadyCallback;
@@ -1378,6 +1378,10 @@ final class NativeMapView implements NativeMap {
     return viewCallback.getHeight();
   }
 
+  long getNativePtr() {
+    return nativePtr;
+  }
+
   //
   // Snapshot
   //