Support headers in publish-properties

[giscardff]

Hey folks,

The shovel plugin allows to change some AMQP Basic Properties value, as listed on this link.

However, sometimes, it might be necessary to change properties not defined on AMQP Specification. For example, in my case I receive messages from dozen of onpremise customers, and I've created a header "tenant" to identify them and want to make sure the Shovel will always overwrite such value is important so customerA doesn't send a menssage using customerB tenant value.

I believe that implement such a feature would be simple for your guys, basically it requires support to change the property "header" of AMQP by sending a map of values.

In order to change the user_id property we have:
publish-properties: {"user_id":"myid"}

In order to change the header properties we would have:
publish-properties: {"headers": {"tenant":"mytenant", "myinteger":10, "myboolean":false}}

Shovel just set the headers as defines (LongString, Integer or Boolean) and if the customer property doesn't match the type, let's say someone has set "tenant" to an integer value; Shovel would simply log and discard the message.

Looking forward for hearing some news 😄