Clearly the right solution is to use XML Object Notation, aka XON™!

JSON:

  {"foo": ["bar", 42]}

XON:

  <Object>
    <Property>
      <Key>foo</Key>
      <Value>
        <Array>
          <String>bar</String>
          <Number>42</Number>
        </Arra>
      </Value>
    </Property>
  </Object>

It gives you all the flexibility of JSON with the mature tooling of XML!

Edit: jesus christ, it actually exists https://sevenval.gitbook.io/flat/reference/templating/oxn

We had an IT guy who once bought an XML<->JSON server for $12,000. Very proud of his rack of "data appliances". It made XML like XON out of JSON and JSON that was a soup of elements attributes and ___content___, thus giving you the complexity of XML in JSON. I don't think it got used once by our dev team, and I'm pretty sure it never processed a byte of anything of value.