Add fromJson method to DirectionsRoute (#696)

Author: danesfeder

services-directions/src/main/java/com/mapbox/api/directions/v5/models/DirectionsRoute.java

@@ -1,10 +1,20 @@
 package com.mapbox.api.directions.v5.models;
 
 import android.support.annotation.Nullable;
+
 import com.google.auto.value.AutoValue;
 import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
 import com.google.gson.TypeAdapter;
 import com.google.gson.annotations.SerializedName;
+import com.mapbox.api.directions.v5.DirectionsAdapterFactory;
+import com.mapbox.geojson.BoundingBox;
+import com.mapbox.geojson.Geometry;
+import com.mapbox.geojson.Point;
+import com.mapbox.geojson.gson.BoundingBoxDeserializer;
+import com.mapbox.geojson.gson.GeoJsonAdapterFactory;
+import com.mapbox.geojson.gson.GeometryDeserializer;
+import com.mapbox.geojson.gson.PointDeserializer;
 
 import java.io.Serializable;
 import java.util.List;
@@ -27,6 +37,24 @@ public static Builder builder() {
     return new AutoValue_DirectionsRoute.Builder();
   }
 
+  /**
+   * Create a new instance of this class by passing in a formatted valid JSON String.
+   *
+   * @param json a formatted valid JSON string defining a GeoJson Directions Route
+   * @return a new instance of this class defined by the values passed inside this static factory
+   *   method
+   * @since 3.0.0
+   */
+  public static DirectionsRoute fromJson(String json) {
+    GsonBuilder gson = new GsonBuilder();
+    gson.registerTypeAdapter(Point.class, new PointDeserializer());
+    gson.registerTypeAdapter(Geometry.class, new GeometryDeserializer());
+    gson.registerTypeAdapter(BoundingBox.class, new BoundingBoxDeserializer());
+    gson.registerTypeAdapterFactory(GeoJsonAdapterFactory.create());
+    gson.registerTypeAdapterFactory(DirectionsAdapterFactory.create());
+    return gson.create().fromJson(json, DirectionsRoute.class);
+  }
+
   /**
    * The distance traveled from origin to destination.
    *