docs: public void markPubKeyHashAsUsed(byte[] pubKeyHash) {
          if (chains != null) {
              for (DeterministicKeyChain chain : chains) {
                  DeterministicKey key;
                  if ((key = chain.markPubHashAsUsed(pubKeyHash)) != null) {
                      maybeMarkCurrentKeyAsUsed(key);
                      return;
                  }
              }
          }
      }