docs: private void removeOldSignedPreKeys(OmemoDevice userDevice) {
          if (OmemoConfiguration.getMaxNumberOfStoredSignedPreKeys() <= 0) {
              return;
          }
  
          TreeMap<Integer, T_SigPreKey> signedPreKeys = loadOmemoSignedPreKeys(userDevice);
  
          for (int i = 0; i < signedPreKeys.keySet().size() - OmemoConfiguration.getMaxNumberOfStoredSignedPreKeys(); i++) {
              int keyId = signedPreKeys.firstKey();
              LOGGER.log(Level.INFO, "Remove signedPreKey " + keyId + ".");
              removeOmemoSignedPreKey(userDevice, i);
              signedPreKeys = loadOmemoSignedPreKeys(userDevice);
          }
      }