in crates/iceberg/src/spec/datatypes.rs [288:295]
fn field_id_to_index(&self, field_id: i32) -> Option<usize> {
self.id_lookup
.get_or_init(|| {
HashMap::from_iter(self.fields.iter().enumerate().map(|(i, x)| (x.id, i)))
})
.get(&field_id)
.copied()
}