Function request_counts_subtree 

pub fn request_counts_subtree(counters: &[AtomicU64; 17]) -> Value

Build the requests subtree: one numeric field per PayloadRequestKind variant, keyed by its Display name, holding the running inbound counter.

Reads use Ordering::Relaxed — counters are advisory metrics, not synchronisation primitives, and the snapshot doesn’t need to be coherent across kinds.