code: protected V getIfCached(@NullableDecl Object key) {
      Entry<K, V> entry = entrySetCache; // store local reference for thread-safety
  
      // Check cache. We use == on purpose because it's cheaper and a cache miss is ok.
      if (entry != null && entry.getKey() == key) {
        return entry.getValue();
      }
      return null;
    }
docs: Internal methods ('protected' is still package-visible, but treat as only subclass-visible)