Base codebehind for JRGroup — the parent of every sub-panel / dialog (and, transitively, every JRScreen). Kept intentionally minimal: it exists only to provide the onDestroy() floor below.

Floor for JRGroup subclasses (panels/dialogs) that DON'T override onDestroy(): abandon any pending fetchAsync promises so a late pool response can't fire a callback into the destroyed node. Subclasses that DO override onDestroy() get this via the auto-abandon-promises BSC plugin (which injects abandonApiPromises() into their own onDestroy) — SG component onDestroy does not chain to this base, so the call can't rely on inheritance alone.