Merge pull request #222 from messagebird/Issue_221_220_fix

fixed objectmapper serialization and updated Language enum class

Author: denizkilic

api/src/main/java/com/messagebird/MessageBirdServiceImpl.java

@@ -590,7 +590,6 @@ public <P> HttpURLConnection getConnection(final String serviceUrl, final P body
             connection.setRequestProperty("Content-Type", "application/json");
             ObjectMapper mapper = new ObjectMapper();
             mapper.setSerializationInclusion(Include.NON_NULL);
-            mapper.enable(SerializationFeature.WRITE_ENUMS_USING_TO_STRING);
             // Specifically set the date format for POST requests so scheduled
             // messages and other things relying on specific date formats don't
             // fail when sending.

api/src/main/java/com/messagebird/objects/Language.java

@@ -1,5 +1,7 @@
 package com.messagebird.objects;
 
+import com.fasterxml.jackson.annotation.JsonValue;
+
 /**
  * Created by faizan on 09/12/15.
  */
@@ -25,13 +27,21 @@ public enum Language {
     PT_BR("pt-br"),
     RO_RO("ro-ro");
 
-    private String code;
+    final String code;
 
     Language(String code) {
        this.code = code;
     }
 
+    @JsonValue
+    public String getCode() {
+        return code;
+    }
+
+    @Override
     public String toString() {
-        return this.code;
+        return "Language{" +
+                "code='" + code + '\'' +
+                '}';
     }
 }