docs: private URL getUrl() {
          ClassLoader loader = null;
          try {
              loader = Thread.currentThread().getContextClassLoader();
          } catch (Exception e) {
              // do nothing
          }
  
          if (loader == null) {
              loader = ClassPathResource.class.getClassLoader();
          }
  
          URL url = loader.getResource(this.resourceName);
          if (url == null) {
              // try to check for mis-used starting slash
              // TODO: see TODO below
              if (this.resourceName.startsWith("/")) {
                  url = loader.getResource(this.resourceName.replaceFirst("[\\\\/]", ""));
                  if (url != null)
                      return url;
              } else {
                  // try to add slash, to make clear it's not an issue
                  // TODO: change this mechanic to actual path purifier
                  url = loader.getResource("/" + this.resourceName);
                  if (url != null)
                      return url;
              }
              throw new IllegalStateException("Resource '" + this.resourceName + "' cannot be found.");
          }
          return url;
      }