### Question:
PolygonStamped extends Message { public static PolygonStamped fromJsonString(String jsonString) { return PolygonStamped.fromMessage(new Message(jsonString)); } PolygonStamped();  PolygonStamped(Header header, Polygon polygon); Header getHeader(); Polygon getPolygon(); @Override PolygonStamped clone(); static PolygonStamped fromJsonString(String jsonString); static PolygonStamped fromMessage(Message m); static PolygonStamped fromJsonObject(JsonObject jsonObject); static final String FIELD_HEADER; static final String FIELD_POLYGON; static final String TYPE; }### Answer:
@Test public void testFromJsonString() { PolygonStamped p = PolygonStamped.fromJsonString(p1.toString()); assertEquals(p1.toString(), p.toString()); assertEquals(p1.toJsonObject(), p.toJsonObject()); assertEquals(p1.getMessageType(), p.getMessageType()); assertEquals(p1.getHeader(), p.getHeader()); assertEquals(p1.getPolygon(), p.getPolygon()); assertNotSame(p1, p); assertNotSame(p1.toString(), p.toString()); assertNotSame(p1.toJsonObject(), p.toJsonObject()); }