Function check_bitmap_operator_class 

pub fn check_bitmap_operator_class<T, K>(
    encode_key: fn(T) -> PluginResult<K>,
) -> PluginResult<()>
where
    T: RadixType + Debug,
    K: OperatorClassKey,

Bitmap keys may coalesce byte representation only when the external values are semantically equal; otherwise exact lookup and uniqueness would diverge.