System for data validation and class generation (Avro vs Json Schema vs OpenAPI)

Question

We want to have a system that allows us to define data schemas that we can use to validate our data, and to generate code in specific languages. We found json schema's that lets us do something like

File "message.json.schema"

{
    "$schema": "https://json-schema.org/draft/2019-09/schema",
    "title": "Message",
    "properties": {
            "name": {
        "type" : "string"
        },
    
            "type": {
                "$ref": "type/message_type.schema.json"
            },

        "message_id":{
            "$ref": "type/uuid.schema.json"
        }
    },
    "required": ["name", "message_id"]
}

File "message_type.json.schema"

{
    "$schema": "https://json-schema.org/draft/2019-09/schema",
    "title": "MessageType",
    "enum": ["Message", "Query"]
}

File "uuid_type.json.schema"

{
    "$schema": "https://json-schema.org/draft/2019-09/schema",
    "title": "UUID",
    "type": "string",
    "pattern": "^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$"
}

File "query.json.schema"

{
    "$schema": "https://json-schema.org/draft/2019-09/schema",
    "title": "Query",
    "allOf" : [ {"$ref": "type/message.schema.json" }],
    "required": ["type"]
}

Please ignore if there is something that doesn't make sense but the point is, we really enjoy this system because it allows us to define types, and to refer to types that we create in another files, and even to use them like for type inheritance.

Then we want to use this files for code generation and validation. In python we then use a library called python_jsonschema_objects that can parse this files and the files that it references recursively, and we can then really simply create a python object with all the validation included.

But then we also want to use them for Java/Kotlin but the library that we found jsonschema2pojo doesn't seem able to parse linked files expecting everything to be in the same file.

This leads us to think that for some reason Json Schema is not that supported or used, unfortunately.

So, we have the question if a system like Avro or OpenAPI would be better supported and more widely used and could be chosen to this type of task.