You can find the source code for the marshaller here: https://github.com/infinispan/infinispan/blob/master/client/hotrod-client/src/main/java/org/infinispan/client/hotrod/marshall/ApacheAvroMarshaller.java
This is very interesting stuff and other people are interested in it as well, would be great if you can contribute it back!
I just feel it is a bit strange I need to look at source code to make the C# counter-part. I thought those ID should be a public contract (i.e. make it as a public ID or have some java-doc)