feat(api): api call to unfollow playlist

Author: Jiankai Zheng

src/main/java/spotify/api/impl/FollowApiRetrofit.java

@@ -167,4 +167,24 @@ public void unfollowEntities(EntityType entityType, List<String> listOfEntityIds
             throw new HttpRequestFailedException(ex.getMessage());
         }
     }
+
+    @Override
+    public void unfollowPlaylist(String playlistId) {
+        logger.trace("Constructing HTTP call to unfollow playlist.");
+        Call<Void> httpCall = followService.unfollowPlaylist("Bearer " + this.accessToken, playlistId);
+
+        try {
+            logger.info("Executing HTTP call to unfollow playlist.");
+            logger.debug(String.format("Unfollowing playlist %s ", playlistId));
+            LoggingUtil.logHttpCall(logger, httpCall);
+            Response<Void> response = httpCall.execute();
+
+            ResponseChecker.throwIfRequestHasNotBeenFulfilledCorrectly(response.errorBody());
+
+            logger.info("Playlist has been successfully unfollowed.");
+        } catch (IOException ex) {
+            logger.error("HTTP request to unfollow playlist has failed.");
+            throw new HttpRequestFailedException(ex.getMessage());
+        }
+    }
 }

src/main/java/spotify/api/interfaces/FollowApi.java

@@ -19,4 +19,5 @@ public interface FollowApi {
 
     void unfollowEntities(EntityType entityType, List<String> listOfEntityIds);
 
+    void unfollowPlaylist(String playlistId);
 }

src/main/java/spotify/api/spotify/SpotifyApi.java

@@ -217,6 +217,11 @@ public void unfollowEntities(EntityType entityType, List<String> listOfEntityIds
         followApi.unfollowEntities(entityType, listOfEntityIds);
     }
 
+    public void unfollowPlaylist(String playlistId) {
+        logger.info("Requesting to unfollow playlist");
+        followApi.unfollowPlaylist(playlistId);
+    }
+
     private void setup(String accessToken) {
         logger.trace("Constructing Retrofit APIs");
         this.trackApi = new TrackApiRetrofit(accessToken);