if (strictParsing) {
      checkState(
          this.maximumSize == UNSET_INT,
          "weigher can not be combined with maximum size (%s provided)",
          this.maximumSize);
    }

    // safely limiting the kinds of caches this can produce
    @SuppressWarnings("unchecked")
    CacheBuilder<K1, V1> me = (CacheBuilder<K1, V1>) this;
    me.weigher = checkNotNull(weigher);
    return me;
  }