Monotonically increasing counter used to guard against race conditions
when the user switches basemaps faster than style.load fires.
Each call to _applyViaStyleChange() increments the counter; the
style.load callback skips work if the generation no longer matches.
Also used by the WMTS async path as a stale-switch guard.
Monotonically increasing counter used to guard against race conditions when the user switches basemaps faster than
style.loadfires. Each call to_applyViaStyleChange()increments the counter; thestyle.loadcallback skips work if the generation no longer matches. Also used by the WMTS async path as a stale-switch guard.