docs: void setError(Exception error) {
      if (this.error != null) {
        throw new IllegalStateException(
            "Cannot reassign the error value of a response!");
      }
      this.error = error;
      this.complete = true;
      try {
        this.states.put(RESPONSE_COMPLETE);
      } catch (InterruptedException e) {
        log.error("Interrupted trying to indicate an error condition.", e);
      }
    }