destroyInternalCache(drawerId = undefined) {
            const internal = this[DRAWER_INTERNAL_CACHE];
            if (internal) {
                if (drawerId) {
                    const cache = internal[drawerId];
                    if (cache) {
                        cache.destroy();
                        delete internal[drawerId];
                    }
                } else {
                    for (let iCache in internal) {
                        internal[iCache].destroy();
                    }
                    delete this[DRAWER_INTERNAL_CACHE];
                }
            }
        }
If cache ceases to be the primary one, free data
@param {string} drawerId if undefined, all caches are freed, else only target one
@private