I have two versions of the same schema where a breaking change has been made. Is there a way to inject code into Avro so that it knows how to deal with this breaking change?

Example:
Schema 1 – the keys are a list of strings

{
   "type":"record",
   "name":"Item",
   "namespace":"com.test",
   "fields":[
      {
         "name":"id",
         "type":"string"
      },
      {
        "name":"keys",
        "type": {
            "type": "array",
            "items": "string"
        }
      }
   ]
}

Schema 2 – the keys are their own distinct record

{
   "type":"record",
   "name":"Item",
   "namespace":"com.test",
   "fields":[
      {
         "name":"id",
         "type":"string"
      },
      {
        "name":"keys",
        "type": {
            "type": "array",
            "items": {
               "type":"record",
               "name":"Key",
               "namespace":"com.test",
               "fields":[
                  {
                    "name":"id",
                    "type":"string"
                  }
                ]
            }
        }
      }
   ]
}

I would like to inject some custom code which converts String into Key objects, and vice-versa.