Serialize taxonomies

Author: rafalniski

src/main/java/com/contentful/java/cma/gson/MetadataSerializer.java

@@ -4,6 +4,7 @@
 import com.contentful.java.cma.model.CMASystem;
 import com.contentful.java.cma.model.CMATag;
 import com.contentful.java.cma.model.CMAType;
+import com.contentful.java.cma.model.CMALink;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
@@ -17,23 +18,56 @@ public class MetadataSerializer implements JsonSerializer<CMAMetadata> {
     @Override
     public JsonElement serialize(CMAMetadata src, Type typeOfSrc, JsonSerializationContext ctx) {
         final JsonObject result = new JsonObject();
+
+        // Always include tags field, even if empty
         result.add("tags", serializeTags(src.getTags()));
+
+        // Serialize concepts if present
+        if (src.getConcepts() != null && !src.getConcepts().isEmpty()) {
+            result.add("concepts", serializeLinks(
+                    src.getConcepts(), CMAType.TaxonomyConcept));
+        }
+
+        // Serialize taxonomies if present
+        if (src.getTaxonomy() != null && !src.getTaxonomy().isEmpty()) {
+            result.add("taxonomy", serializeLinks(
+                    src.getTaxonomy(), CMAType.TaxonomyConceptScheme));
+        }
+
         return result;
     }
 
     private JsonArray serializeTags(List<CMATag> tags) {
         JsonArray jsonArray = new JsonArray();
-        for (CMATag tag : tags) {
-            JsonObject tagObject = new JsonObject();
+        if (tags != null) {
+            for (CMATag tag : tags) {
+                JsonObject tagObject = new JsonObject();
+                JsonObject sysObject = new JsonObject();
+                CMASystem system = tag.getSystem();
+
+                sysObject.addProperty("type", CMAType.Link.toString());
+                sysObject.addProperty("linkType", CMAType.Tag.toString());
+                sysObject.addProperty("id", system.getId());
+
+                tagObject.add("sys", sysObject);
+                jsonArray.add(tagObject);
+            }
+        }
+        return jsonArray;
+    }
+
+    private JsonArray serializeLinks(List<CMALink> links, CMAType linkType) {
+        JsonArray jsonArray = new JsonArray();
+        for (CMALink link : links) {
+            JsonObject linkObject = new JsonObject();
             JsonObject sysObject = new JsonObject();
-            CMASystem system = tag.getSystem();
 
             sysObject.addProperty("type", CMAType.Link.toString());
-            sysObject.addProperty("linkType", CMAType.Tag.toString());
-            sysObject.addProperty("id", system.getId());
+            sysObject.addProperty("linkType", linkType.toString());
+            sysObject.addProperty("id", link.getId());
 
-            tagObject.add("sys", sysObject);
-            jsonArray.add(tagObject);
+            linkObject.add("sys", sysObject);
+            jsonArray.add(linkObject);
         }
         return jsonArray;
     }