code: @Override
    public final API withInjectedLogSite(LogSite logSite) {
      // First call wins (since auto-injection will typically target the log() method at the end of
      // the chain and might not check for previous explicit injection).
      if (this.logSite == null) {
        this.logSite = checkNotNull(logSite, "log site");
      }
      return api();
    }
docs: ---- Log site injection (used by pre-processors and special cases) ----