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This protocol is out of scope of this proposal.

Proposed changes

OnDiscoveryNodeValidationProcessor

This processor validates version of joining node. It should validate that versions differ on 1 minor version only.

Message DTO

There should be one serialization framework for communication and discovery protocol. 

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1. MessageWriter, MessageReader logic is depends on a remote IgniteProductVersion.
2. Message#writeTo, Message#readFrom is auto-generated and stored separately from Message DTO classes.
3. Add Message#writeJavaObject - for serializing Java functions and user objects (ComputeJob, etc) with JdkMarshaller.
4. Message fields contain:
   1. primitive classes
   2. known collections
   3. POJO - that are other Message
   4. Users classes and java functions (e.g. ComputeJob).
   5. byte[] fields (objects serialized externally) must be avoided as much as possible, because their compatibility can't be guaranteed
5. Add @Since, @Until  annotations for Message classes and fields.

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