public Optional<?> body() {
		return Optional.ofNullable(body);
	}
Return the resource body. The body will be set by the
{@link #PUT(Object, Caller)} and {@link #POST(Object, Caller)} methods
and is then available for the {@link Caller}.

@return the resource body
jenetics.incubator/src/main/java/io/jenetics/incubator/restful/Resource.java