Remove unused classes

package com.fsck.k9

fun interface SettingsChangeListener {

    fun onSettingsChanged()

}

package com.fsck.k9.activity.misc;

import android.app.Activity;

public interface NonConfigurationInstance {

    /**

     * Decide whether to retain this {@code NonConfigurationInstance} and clean up resources if

     * necessary.

     *

     * <p>

     * This needs to be called when the current activity is being destroyed during an activity

     * restart due to a configuration change.<br>

     * Implementations should make sure that references to the {@code Activity} instance that is

     * about to be destroyed are cleared to avoid memory leaks. This includes all UI elements that

     * are bound to an activity (e.g. dialogs). They can be re-created in

     * {@link #restore(Activity)}.

     * </p>

     *

     * @return {@code true} if this instance should be retained; {@code false} otherwise.

     *

     * @see Activity#onRetainNonConfigurationInstance()

     */

    boolean retain();

    /**

     * Connect this retained {@code NonConfigurationInstance} to the new {@link Activity} instance

     * after the activity was restarted due to a configuration change.

     *

     * <p>

     * This also creates a new progress dialog that is bound to the new activity.

     * </p>

     *

     * @param activity

     *         The new {@code Activity} instance. Never {@code null}.

     */

    void restore(Activity activity);

}

package com.fsck.k9.mail.oauth;

public class AuthorizationException extends Exception {

    public AuthorizationException(String detailMessage, Throwable throwable) {

        super(detailMessage, throwable);

    }

    public AuthorizationException(String detailMessage) {

        super(detailMessage);

    }

}