@Override
	public String convert(Tuple source) {
		ObjectNode root = toObjectNode(source);
		String json = null;
		try {
			json = mapper.writeValueAsString(root);
		}
		catch (Exception e) {
			throw new IllegalArgumentException("Tuple to string conversion failed", e);
		}
		return json;
	}
Converts a Tuple to JSON representation

@author David Turanski
@author Gunnar Hillert
spring-xd-tuple/src/main/java/org/springframework/xd/tuple/TupleToJsonStringConverter.java