Add offset to Time, for WatchFace app on the Android Wear

OffsetTime.java

package jp.kshoji.watchface;

import android.support.annotation.NonNull;
import android.text.format.Time;

/**
 * <h2>Time with Offset</h2>
 *
 * For example, construct an instance with `new Offset(300);`,
 * When the real time: `9:00`, this OffsetTime returns `9:05`
 *
 * @author K.Shoji
 * @license <a href="http://www.apache.org/licenses/LICENSE-2.0.html">Apache License, Version 2.0</a>
 */
public class OffsetTime extends Time {
    private long offsetMillis;

    /**
     * Default constructor; Same behaviour as {@link Time}
     */
    public OffsetTime() {
        offsetMillis = 0L;
    }

    /**
     * Construct with offset
     *
     * @param offsetSeconds Time offsets in seconds
     */
    public OffsetTime(int offsetSeconds) {
        offsetMillis = offsetSeconds * 1000L;
    }

    @Override
    public void set(long millis) {
        super.set(millis + offsetMillis);
    }

    @Override
    public void set(int monthDay, int month, int year) {
        super.set(monthDay, month, year);
        set(toMillis(false) + offsetMillis);
    }

    @Override
    public void set(int second, int minute, int hour, int monthDay, int month, int year) {
        super.set(second, minute, hour, monthDay, month, year);
        set(toMillis(false) + offsetMillis);
    }

    @Override
    public void set(@NonNull Time that) {
        super.set(that);
        set(toMillis(false) + offsetMillis);
    }
}