### Question:
PayloadBuilder { @Override public String toString() { return this.build(); } PayloadBuilder(); private  PayloadBuilder(Map<String, Object> root,
            Map<String, Object> aps,
            Map<String, Object> customAlert); PayloadBuilder alertBody(String alert); PayloadBuilder sound(String sound); PayloadBuilder badge(int badge); PayloadBuilder clearBadge(); PayloadBuilder actionKey(String actionKey); PayloadBuilder noActionButton(); PayloadBuilder forNewsstand(); PayloadBuilder localizedKey(String key); PayloadBuilder localizedArguments(Collection<String> arguments); PayloadBuilder localizedArguments(String... arguments); PayloadBuilder launchImage(String launchImage); PayloadBuilder customField(String key, Object value); PayloadBuilder mdm(String s); PayloadBuilder customFields(Map<String, ? extends Object> values); int length(); boolean isTooLong(); PayloadBuilder resizeAlertBody(int payloadLength); PayloadBuilder resizeAlertBody(int payloadLength, String postfix); PayloadBuilder shrinkBody(); PayloadBuilder shrinkBody(String postfix); String build(); byte[] buildBytes(); @Override String toString(); PayloadBuilder copy(); static PayloadBuilder newPayload();  }### Answer:
@Test public void testEmpty() { PayloadBuilder builder = new PayloadBuilder(); String expected = "{\"aps\":{}}"; String actual = builder.toString(); assertEqualsJson(expected, actual); }