When receiving a message, and when auto-acknowledgement is disabled, this method is used to acknowledge
the incoming message. It marks the message as delivered with the {@code accepted} status.
@return the current {@link AmqpMessage} object
@throws IllegalStateException is the current message is not a received message.
When receiving a message, and when auto-acknowledgement is disabled, this method is used to acknowledge the incoming message. It marks the message as delivered with the {@code accepted} status.
@return the current {@link AmqpMessage} object @throws IllegalStateException is the current message is not a received message.