src/vs/workbench/api/common/extHostLanguageFeatures.ts/InlayHintsAdapter/resolveInlayHint
class InlayHintsAdapter:	async resolveInlayHint(id: extHostProtocol.ChainedCacheId, token: CancellationToken) {
		if (typeof this._provider.resolveInlayHint !== 'function') {
			return undefined;
		}
		const item = this._cache.get(...id);
		if (!item) {
			return undefined;
		}
		const hint = await this._provider.resolveInlayHint!(item, token);
		if (!hint) {
			return undefined;
		}
		if (!this._isValidInlayHint(hint)) {
			return undefined;
		}
		return this._convertInlayHint(hint, id);
	}