Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.util.Set
            at android.app.SharedPreferencesImpl.getStringSet(SharedPreferencesImpl.java:232)
            at android.preference.Preference.getPersistedStringSet(Preference.java:1484)
            at android.preference.MultiSelectListPreference.onSetInitialValue(MultiSelectListPreference.java:224)
            at android.preference.Preference.dispatchSetInitialValue(Preference.java:1345)
            at android.preference.Preference.onAttachedToHierarchy(Preference.java:1140)
            at android.preference.PreferenceGroup.addPreference(PreferenceGroup.java:163)
            at android.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:104)
            at android.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:45)
            at android.preference.GenericInflater.rInflate(GenericInflater.java:488)
            at android.preference.GenericInflater.rInflate(GenericInflater.java:493)
            at android.preference.GenericInflater.inflate(GenericInflater.java:326)
            at android.preference.GenericInflater.inflate(GenericInflater.java:263)
            at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:272)
            at android.preference.PreferenceFragment.addPreferencesFromResource(PreferenceFragment.java:285)
            at SettingsActivity$PreferenceFragment.onCreate(SettingsActivity.java:37)
            at android.app.Fragment.performCreate(Fragment.java:1678)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:859)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
            at android.app.BackStackRecord.run(BackStackRecord.java:684)
            at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
            at android.app.Activity.performStart(Activity.java:5240)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2157)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)