sample.avsc

{
    "type": "record",
    "name": "UserCreated",
    "namespace": "com.example.events",
    "fields": [
      {"name": "id", "type": "string"},
      {"name": "email", "type": "string"},
      {"name": "age", "type": ["null", "int"], "default": null},
      {"name": "tags", "type": {"type": "array", "items": "string"}, "default": []},
      {"name": "source", "type": {"type": "enum", "name": "Source", "symbols": ["web", "mobile", "api"]}}
    ]
}