Builder to create a new {@link AmqpMessage}. <p> Reference about the different metadata can be found on <a href="http://docs.oasis-open.org/amqp/core/v1.0/amqp-core-messaging-v1.0.html#type-properties">AMQP message properties</a>. <p> Note that the body is set using {@code withBodyAs*} method depending on the passed type.