How to pass array of objects as parameter in firebase analytics custom events

We are trying to capture the API details on our website. So we are logging a custom event inside the Axios interceptors. So we need to send a nested object(which contains all the details of the API call) as a parameter in the custom_events. But when I am sending it firebase is not accepting. So I think firebase only accepts it in the form of items parameter. But when I am using the items param(parcelable item) it is not showing it in the debug view. Is there any way we can send our own custom object inside a single parameter in custom Events

logEvent(
  analytics,
  'studio_metrics',
  {
    items: [{
      name: 'Kittens',
      age: 10
    }, {
      name: 'prabhakar',
      age: 12
    }]
  }
)

I am adding like this but it didn't work. If I am sending it via a predefined event like 'purchase' it is working fine. I am using react here.