code: public static Resource exists(final String resource)
     {
        return new Resource(resource) {
           @Override
           public String toString()
           {
              return "Resource.exists(\"" + resource + "\")";
           }
        };
     }
docs: Create a {@link Condition} that returns <code>true</code> if the given resource exists in the
  {@link ServletContext#getResourcePaths(String)} of the current application.
  
  <p>
  The given resource path may be parameterized:
  <p>
  <code>
  /example/{param}.html <br>
  /css/{value}.css <br>
  ...
  </code>
  <p>
  
  @param location {@link ParameterizedPattern} specifying the {@link Address} of the internal resource.
  
  @see {@link ConfigurationRuleParameterBuilder#where(String)}