Rust: Record serialization is sensitive to order of fields in struct

#[derive(Deserialize, Serialize)]
pub struct MyRecord {
  b: String,
  a: i64,
}
 

{
  "type": "record",
  "name": "my_record",
  "fields": [
    {"name": "a", "type": "long"},
    {"name": "b", "type": "string"},
  ]
}