Reduce visibility of GeoJsonSerializersModule.

This commit reduces the visibility of the GeoJsonSerializersModule and instead offers static methods on GeoJsonModule allowing to obtain those via a static method.
The actual serialization was simpified by moving some of its code to a common base class.
Updated reference documentation - relates to: spring-projects/spring-data-commons#2288

We also did, by intend, not change the current GeoJsonModule to add the serializers by default in order to give users time to prepare for that change which will be done with the next major release.

Author: christophstrobl

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/geo/GeoJsonModule.java

@@ -21,10 +21,16 @@
 import java.util.List;
 
 import org.springframework.data.geo.Point;
+import org.springframework.data.mongodb.core.geo.GeoJsonSerializersModule.GeoJsonLineStringSerializer;
+import org.springframework.data.mongodb.core.geo.GeoJsonSerializersModule.GeoJsonMultiLineStringSerializer;
+import org.springframework.data.mongodb.core.geo.GeoJsonSerializersModule.GeoJsonMultiPointSerializer;
+import org.springframework.data.mongodb.core.geo.GeoJsonSerializersModule.GeoJsonMultiPolygonSerializer;
+import org.springframework.data.mongodb.core.geo.GeoJsonSerializersModule.GeoJsonPointSerializer;
+import org.springframework.data.mongodb.core.geo.GeoJsonSerializersModule.GeoJsonPolygonSerializer;
 import org.springframework.lang.Nullable;
 
 import com.fasterxml.jackson.core.JsonParser;
-import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.Version;
 import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.JsonDeserializer;
 import com.fasterxml.jackson.databind.JsonNode;
@@ -34,7 +40,10 @@
 import com.fasterxml.jackson.databind.node.ArrayNode;
 
 /**
- * A Jackson {@link Module} to register custom {@link JsonSerializer} and {@link JsonDeserializer}s for GeoJSON types.
+ * A Jackson {@link Module} to register custom {@link JsonDeserializer}s for GeoJSON types.
+ * <p />
+ * Use {@link #geoJsonModule()} to obtain a {@link Module} containing both {@link JsonSerializer serializers} and
+ * {@link JsonDeserializer deserializers}.
  *
  * @author Christoph Strobl
  * @author Oliver Gierke
@@ -47,12 +56,97 @@ public class GeoJsonModule extends SimpleModule {
 
 	public GeoJsonModule() {
 
-		addDeserializer(GeoJsonPoint.class, new GeoJsonPointDeserializer());
-		addDeserializer(GeoJsonMultiPoint.class, new GeoJsonMultiPointDeserializer());
-		addDeserializer(GeoJsonLineString.class, new GeoJsonLineStringDeserializer());
-		addDeserializer(GeoJsonMultiLineString.class, new GeoJsonMultiLineStringDeserializer());
-		addDeserializer(GeoJsonPolygon.class, new GeoJsonPolygonDeserializer());
-		addDeserializer(GeoJsonMultiPolygon.class, new GeoJsonMultiPolygonDeserializer());
+		registerDeserializersIn(this);
+		// TODO: add serializers as of next major version (4.0).
+	}
+
+	/**
+	 * Obtain a {@link Module} containing {@link JsonDeserializer deserializers} for the following {@link GeoJson} types:
+	 * <ul>
+	 * <li>{@link GeoJsonPoint}</li>
+	 * <li>{@link GeoJsonMultiPoint}</li>
+	 * <li>{@link GeoJsonLineString}</li>
+	 * <li>{@link GeoJsonMultiLineString}</li>
+	 * <li>{@link GeoJsonPolygon}</li>
+	 * <li>{@link GeoJsonMultiPolygon}</li>
+	 * </ul>
+	 * 
+	 * @return a {@link Module} containing {@link JsonDeserializer deserializers} for {@link GeoJson} types.
+	 * @since 3.2
+	 */
+	public static Module deserializers() {
+
+		SimpleModule module = new SimpleModule("Spring Data MongoDB GeoJson - Deserializers",
+				new Version(3, 2, 0, null, "org.springframework.data", "spring-data-mongodb-geojson"));
+		registerDeserializersIn(module);
+		return module;
+	}
+
+	/**
+	 * Obtain a {@link Module} containing {@link JsonSerializer serializers} for the following {@link GeoJson} types:
+	 * <ul>
+	 * <li>{@link GeoJsonPoint}</li>
+	 * <li>{@link GeoJsonMultiPoint}</li>
+	 * <li>{@link GeoJsonLineString}</li>
+	 * <li>{@link GeoJsonMultiLineString}</li>
+	 * <li>{@link GeoJsonPolygon}</li>
+	 * <li>{@link GeoJsonMultiPolygon}</li>
+	 * </ul>
+	 *
+	 * @return a {@link Module} containing {@link JsonSerializer serializers} for {@link GeoJson} types.
+	 * @since 3.2
+	 */
+	public static Module serializers() {
+
+		SimpleModule module = new SimpleModule("Spring Data MongoDB GeoJson - Serializers",
+				new Version(3, 2, 0, null, "org.springframework.data", "spring-data-mongodb-geojson"));
+		registerSerializersIn(module);
+		return module;
+	}
+
+	/**
+	 * Obtain a {@link Module} containing {@link JsonSerializer serializers} and {@link JsonDeserializer deserializers}
+	 * for the following {@link GeoJson} types:
+	 * <ul>
+	 * <li>{@link GeoJsonPoint}</li>
+	 * <li>{@link GeoJsonMultiPoint}</li>
+	 * <li>{@link GeoJsonLineString}</li>
+	 * <li>{@link GeoJsonMultiLineString}</li>
+	 * <li>{@link GeoJsonPolygon}</li>
+	 * <li>{@link GeoJsonMultiPolygon}</li>
+	 * </ul>
+	 *
+	 * @return a {@link Module} containing {@link JsonSerializer serializers} and {@link JsonDeserializer deserializers}
+	 *         for {@link GeoJson} types.
+	 * @since 3.2
+	 */
+	public static Module geoJsonModule() {
+
+		SimpleModule module = new SimpleModule("Spring Data MongoDB GeoJson",
+				new Version(3, 2, 0, null, "org.springframework.data", "spring-data-mongodb-geojson"));
+		registerSerializersIn(module);
+		registerDeserializersIn(module);
+		return module;
+	}
+
+	private static void registerSerializersIn(SimpleModule module) {
+
+		module.addSerializer(GeoJsonPoint.class, new GeoJsonPointSerializer());
+		module.addSerializer(GeoJsonMultiPoint.class, new GeoJsonMultiPointSerializer());
+		module.addSerializer(GeoJsonLineString.class, new GeoJsonLineStringSerializer());
+		module.addSerializer(GeoJsonMultiLineString.class, new GeoJsonMultiLineStringSerializer());
+		module.addSerializer(GeoJsonPolygon.class, new GeoJsonPolygonSerializer());
+		module.addSerializer(GeoJsonMultiPolygon.class, new GeoJsonMultiPolygonSerializer());
+	}
+
+	private static void registerDeserializersIn(SimpleModule module) {
+
+		module.addDeserializer(GeoJsonPoint.class, new GeoJsonPointDeserializer());
+		module.addDeserializer(GeoJsonMultiPoint.class, new GeoJsonMultiPointDeserializer());
+		module.addDeserializer(GeoJsonLineString.class, new GeoJsonLineStringDeserializer());
+		module.addDeserializer(GeoJsonMultiLineString.class, new GeoJsonMultiLineStringDeserializer());
+		module.addDeserializer(GeoJsonPolygon.class, new GeoJsonPolygonDeserializer());
+		module.addDeserializer(GeoJsonMultiPolygon.class, new GeoJsonMultiPolygonDeserializer());
 	}
 
 	/**
@@ -67,8 +161,7 @@ private static abstract class GeoJsonDeserializer<T extends GeoJson<?>> extends
 		 */
 		@Nullable
 		@Override
-		public T deserialize(@Nullable JsonParser jp, @Nullable DeserializationContext ctxt)
-				throws IOException, JsonProcessingException {
+		public T deserialize(@Nullable JsonParser jp, @Nullable DeserializationContext ctxt) throws IOException {
 
 			JsonNode node = jp.readValueAsTree();
 			JsonNode coordinates = node.get("coordinates");