code: @Override
      public void verify(Parameter p) throws NamespaceSyntaxWarning,
              IndexingFailure,
              ResourceDownloadError {
          if (nulls(p, p.getValue())) {
              throw new InvalidArgument("p", p);
          }
  
          Namespace ns = p.getNamespace();
          if (ns == null) {
              return;
          }
  
          String resourceLocation = ns.getResourceLocation();
          if (resourceLocation == null) {
              throw new InvalidArgument("resourceLocation", resourceLocation);
          }
  
          // check and open namespace for this parameter, if it has one
          synchronized (resourceLocation) {
              if (!isOpen(resourceLocation)) {
                  final String indexPath = doCompile(resourceLocation);
                  openNamespace(resourceLocation, indexPath);
              }
          }
  
          doVerify(p);
      }
docs: {@inheritDoc}