AsyncAPI: schemaFormat and additional specifications

[char0n]

Message Object and Message Trait Object can defined a field called schemaFormat. This allows to define a format/language for a payload field. AsyncAPI 2.2.x spec mandates that we MUST support following formats:

• AsyncAPI 2.2.0 Schema Object
• JSON Schema Draft 07

The specification further specify that it RECOMMENDS to support following formats:

• Avro 1.9.0 schema
• OpenAPI 3.0.0 Schema Object
• RAML 1.0 data type

We currently only support AsyncAPI 2.2.0 Schema Object. If other schemaFormat is specified the result of parsing is generic ApiDOM object element.

[char0n]

We should introduce support for JSON Schema Draft 07. The question is how to do it. I suggest following as a POC:

Introduce JSON Schema Draft 07 as a separate namespace. This namespace will be able to parse, refract, dereference and resolve itself. Then we hook this namespace to AsyncAPI 2.3 namespace. Other RECOMMENDED AsyncAPI 2.3 schema formats can be adopted in the same way, if this proves as a way to go.

The benefit of this will be that we will have independent namespaces for different JSON Schema versions which we can then incorporate into another namespaces. We can extract OpenAPI 3.1 schema object (2020-12) into separate namespace and then incorporate it back. This will allow us to reuse the JSON Schema 2020-12 in AsyncAPI 2.3 as well.