Setting headers on messages

Messages sent over the event bus can also contain headers.

This can be specified by providing a headers object inside the DeliveryOptions object when sending or publishing:

options = {
 headers: {
   'some-header' => 'some-value'
 }
}
vertx.event_bus().send("news.uk.sport", "Yay! Someone kicked a ball", options)

On the other side, the consumer can retrieve the message header as follows:

eb = $vertx.event_bus()
eb.consumer("news.uk.sport") { |message|
 puts message.headers().get("some-header")
}