oneOf support bug

[AlbertoLopSie]

Describe the bug

I can confirm that #78 is still present

How to Reproduce

Perfectly defined in #78

Expected behavior

A clear and concise description of what you expected to happen.

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[doodzio]

Seems that the problem is https://github.com/asyncapi/parser-js/blob/58f9db60d969723366b8380eb2182414cf774206/src/old-api/operation.ts#L31

    message(index) {
        const message = this._json.message;
        if (!message)
            return null;
        if (message.oneOf && message.oneOf.length === 1)
            return new message_1.Message(message.oneOf[0]);
        if (!message.oneOf)
            return new message_1.Message(message);
        if (typeof index !== 'number')
            return null;
        if (index > message.oneOf.length - 1)
            return null;
        return new message_1.Message(message.oneOf[+index]);
    }
}
exports.Operation = Operation;

It is referred in e.g:

• https://github.com/asyncapi/python-paho-template/blob/471d9b0b98aaf9f6bcae85d382d6a1edbb48bd1d/filters/all.js#L112