code: @Nonnull
    public static ValidationSource createXMLSource (@Nonnull final IReadableResource aResource)
    {
      // Read on demand only
      return new ValidationSource (aResource.getPath (), () -> DOMReader.readXMLDOM (aResource), false)
      {
        @Override
        @Nonnull
        public Source getAsTransformSource ()
        {
          // Use resource as TransformSource to get error line and column
          return TransformSourceFactory.create (aResource);
        }
      };
    }
docs: Assume the provided resource as an XML file, parse it and use the contained
  DOM Node as the basis for validation.
  
  @param aResource
  The original resource. May not be <code>null</code>.
  @return The validation source to be used. Never <code>null</code>.