diff --git a/app/build.gradle b/app/build.gradle
index 9f8c1a2..c485653 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -10,13 +10,6 @@ android {
         versionName "3.2.1.0"
         archivesBaseName = "moasdawiki-" + versionName + "-" + versionCode
     }
-    sourceSets {
-        main {
-            java {
-                exclude "net/moasdawiki/plugin/sync/SynchronizationPlugin*"
-            }
-        }
-    }
     compileOptions {
         sourceCompatibility JavaVersion.VERSION_11
         targetCompatibility JavaVersion.VERSION_11
@@ -28,7 +21,7 @@ android {
 }
 
 dependencies {
-    implementation 'net.moasdawiki:moasdawiki-server:3.2.1'
+    implementation 'net.moasdawiki:moasdawiki-server:3.4.4'
     implementation fileTree(include: ['*.jar'], dir: 'libs')
     implementation 'androidx.appcompat:appcompat:1.4.1'
     // androidx.preference 1.2.0 causes dependency conflict
diff --git a/app/src/main/java/net/moasdawiki/app/MainActivity.java b/app/src/main/java/net/moasdawiki/app/MainActivity.java
index 318bec9..009ed35 100644
--- a/app/src/main/java/net/moasdawiki/app/MainActivity.java
+++ b/app/src/main/java/net/moasdawiki/app/MainActivity.java
@@ -52,7 +52,8 @@ import androidx.preference.PreferenceManager;
 
 import net.moasdawiki.base.ServiceException;
 import net.moasdawiki.base.Settings;
-import net.moasdawiki.server.HttpRequest;
+import net.moasdawiki.http.ContentType;
+import net.moasdawiki.http.HttpRequest;
 import net.moasdawiki.server.RequestDispatcher;
 import net.moasdawiki.service.HttpResponse;
 import net.moasdawiki.service.repository.RepositoryService;
@@ -175,8 +176,14 @@ public class MainActivity extends AppCompatActivity {
                     HttpResponse response = requestDispatcher.handleRequest(httpRequest);
 
                     // send wiki content to browser
-                    InputStream responseData = new ByteArrayInputStream(response.content);
-                    return new WebResourceResponse(response.contentType, "UTF-8", responseData);
+                    String mimeType;
+                    if (response.getContentType() != null) {
+                        mimeType = response.getContentType().getMediaType();
+                    } else {
+                        mimeType = ContentType.BINARY.getMediaType();
+                    }
+                    InputStream responseData = new ByteArrayInputStream(response.getContent());
+                    return new WebResourceResponse(mimeType, "UTF-8", responseData);
                 } catch (IOException e) {
                     e.printStackTrace();
                 }
@@ -270,15 +277,15 @@ public class MainActivity extends AppCompatActivity {
         }
     }
 
-    public void onConfigurationHintClicked(View view) {
+    public void onConfigurationHintClicked(@SuppressWarnings("unused") View view) {
         showSettingsDialog();
     }
 
-    public void onSynchronizeHintClicked(View view) {
+    public void onSynchronizeHintClicked(@SuppressWarnings("unused") View view) {
         synchronizeWithServer();
     }
 
-    public void onSearch(View view) {
+    public void onSearch(@SuppressWarnings("unused") View view) {
         EditText searchInput = findViewById(R.id.search_input);
         String query = searchInput.getText().toString();
         query = query.trim();
diff --git a/app/src/main/java/net/moasdawiki/app/SettingsFragment.java b/app/src/main/java/net/moasdawiki/app/SettingsFragment.java
index 767ca1e..e4bb514 100644
--- a/app/src/main/java/net/moasdawiki/app/SettingsFragment.java
+++ b/app/src/main/java/net/moasdawiki/app/SettingsFragment.java
@@ -49,6 +49,7 @@ public class SettingsFragment extends PreferenceFragmentCompat implements Shared
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        @SuppressWarnings("ConstantConditions")
         WikiEngineApplication app = (WikiEngineApplication) getContext().getApplicationContext();
         synchronizeWikiClient = app.getSynchronizeWikiClient();
         repositoryService = app.getRepositoryService();
diff --git a/app/src/main/java/net/moasdawiki/app/SynchronizeWikiClient.java b/app/src/main/java/net/moasdawiki/app/SynchronizeWikiClient.java
index afcac43..e4e0d33 100644
--- a/app/src/main/java/net/moasdawiki/app/SynchronizeWikiClient.java
+++ b/app/src/main/java/net/moasdawiki/app/SynchronizeWikiClient.java
@@ -167,7 +167,6 @@ public class SynchronizeWikiClient {
         return new BigInteger(130, random).toString(32);
     }
 
-    @NotNull
     private boolean[] checkSession(@NotNull String serverHostPort) throws ServiceException {
         SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(mContext);
         String serverSessionId = preferences.getString(Constants.PREFERENCES_SYNC_SERVER_SESSION_ID, null);
@@ -409,9 +408,8 @@ public class SynchronizeWikiClient {
             while ((bytesRead = in.read(buffer)) != -1) {
                 byteStream.write(buffer, 0, bytesRead);
             }
-            byte[] responseBytes = byteStream.toByteArray();
 
-            String responseXml = new String(responseBytes, StandardCharsets.UTF_8);
+            String responseXml = byteStream.toString("UTF-8");
             Log.d(TAG, "Response: " + truncateLogText(responseXml, 400));
             return responseXml;
         } catch (Exception e) {