Add Google Maps legalNotice constant

lib/android/src/main/java/com/airbnb/android/react/maps/AirMapModule.java

@@ -15,13 +15,17 @@
 import com.facebook.react.uimanager.UIBlock;
 import com.facebook.react.uimanager.UIManagerModule;
 import com.google.android.gms.maps.GoogleMap;
+import com.google.android.gms.common.GoogleApiAvailability;
 
 import java.io.ByteArrayOutputStream;
 import java.io.Closeable;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 
+import java.util.Map;
+import java.util.HashMap;
+
 import javax.annotation.Nullable;
 
 public class AirMapModule extends ReactContextBaseJavaModule {
@@ -40,6 +44,13 @@ public String getName() {
     return "AirMapModule";
   }
 
+  @Override
+  public Map<String, Object> getConstants() {
+    final Map<String, Object> constants = new HashMap<>();
+    constants.put("legalNotice", GoogleApiAvailability.getInstance().getOpenSourceSoftwareLicenseInfo(getReactApplicationContext()));
+    return constants;
+  }
+
   public Activity getActivity() {
     return getCurrentActivity();
   }

lib/ios/AirGoogleMaps/AIRGoogleMapManager.m

@@ -222,6 +222,9 @@ - (UIView *)view
   }];
 }
 
+- (NSDictionary *)constantsToExport {
+  return @{ @"legalNotice": [GMSServices openSourceLicenseInfo] };
+}
 
 - (void)mapViewDidFinishTileRendering:(GMSMapView *)mapView {
     AIRGoogleMap *googleMapView = (AIRGoogleMap *)mapView;