Fixed GeoJSON serialization of MULTIPOINT (#212)

Author: PapaStan

CHANGES.md

@@ -1,5 +1,7 @@
 ## VERSION X.X
 
+* \#210: Fixed GeoJSON serialization of multipoints (Stanislas Courouble)
+
 * \#206: Upgraded to JTS 1.18.1.  This JTS release had an incompatible [API change](https://github.com/locationtech/jts/blob/master/doc/JTS_Version_History.md#api-changes) and it requires Java 1.8.
   Only Spatial4j's `JtsBinaryCodec` was impacted, and thus only use of this will require a JTS upgrade.
 (Christian Marsch)

src/main/java/org/locationtech/spatial4j/io/jackson/GeometryAsGeoJSONSerializer.java

@@ -95,7 +95,6 @@ public void serialize(Geometry geom, JsonGenerator gen, SerializerProvider seria
       MultiPoint v = (MultiPoint) geom;
       gen.writeFieldName("coordinates");
       write(gen, v.getCoordinates());
-      return;
     } else if (geom instanceof MultiLineString) {
       MultiLineString v = (MultiLineString) geom;
       gen.writeFieldName("coordinates");