### Question:
DefaultJsonEnvelope implements JsonEnvelope { @Override public JsonString payloadAsJsonString() { return (JsonString) payload; } DefaultJsonEnvelope(final Metadata metadata, final JsonValue payload); @Override Metadata metadata(); @Override JsonValue payload(); @Override JsonObject payloadAsJsonObject(); @Override JsonArray payloadAsJsonArray(); @Override JsonNumber payloadAsJsonNumber(); @Override JsonString payloadAsJsonString(); @Override JsonObject asJsonObject(); @Override String toString(); @Override String toDebugStringPrettyPrint(); @Override String toObfuscatedDebugString();  }### Answer:
@Test public void shouldReturnPayloadAsJsonString() { assertThat(envelopeFrom(metadata, payloadAsJsonString).payloadAsJsonString(), equalTo(payloadAsJsonString)); }