Let folder display name default to folder name

.idea/misc.xml

@@ -25,7 +25,7 @@
       </value>
     </option>
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_7" project-jdk-name="1.8" project-jdk-type="JavaSDK">
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" project-jdk-name="1.8" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/build/classes" />
   </component>
   <component name="ProjectType">

app/src/main/java/eu/faircode/email/FragmentFolder.java

@@ -120,7 +120,7 @@ public class FragmentFolder extends FragmentEx {
                         boolean unified = args.getBoolean("unified");
                         String after = args.getString("after");
 
-                        if (TextUtils.isEmpty(display))
+                        if (TextUtils.isEmpty(display) || display.equals(name))
                             display = null;
                         int days = (TextUtils.isEmpty(after) ? EntityFolder.DEFAULT_USER_SYNC : Integer.parseInt(after));
 
@@ -312,7 +312,7 @@ public class FragmentFolder extends FragmentEx {
 
                 if (savedInstanceState == null) {
                     etRename.setText(folder == null ? null : folder.name);
-                    etDisplay.setText(folder == null ? null : folder.display);
+                    etDisplay.setText(folder == null ? null : (folder.display == null ? folder.name : folder.display));
                     etDisplay.setHint(folder == null ? null : folder.name);
                     cbUnified.setChecked(folder == null ? false : folder.unified);
                     etAfter.setText(Integer.toString(folder == null ? EntityFolder.DEFAULT_USER_SYNC : folder.after));