docs: public void register( Map<String, String> namespaceUrisByPrefix ) {
          if (namespaceUrisByPrefix == null || namespaceUrisByPrefix.isEmpty()) return;
          final Lock lock = this.namespacesLock.writeLock();
          try {
              lock.lock();
              SystemContent systemContent = systemContent(false);
              systemContent.registerNamespaces(namespaceUrisByPrefix);
              systemContent.save();
              for (Map.Entry<String, String> entry : namespaceUrisByPrefix.entrySet()) {
                  String prefix = entry.getKey().trim();
                  String uri = entry.getValue().trim();
                  if (prefix.length() == 0) continue;
                  this.cache.register(prefix, uri);
              }
          } finally {
              lock.unlock();
          }
      }