code: @SuppressWarnings({"WeakerAccess", "unused"})
     public PreserveAspectRatio  getDocumentPreserveAspectRatio()
     {
        if (this.rootElement == null)
           throw new IllegalArgumentException("SVG document is empty");
  
        if (this.rootElement.preserveAspectRatio == null)
           return null;
  
        return this.rootElement.preserveAspectRatio;
     }
docs: Return the "preserveAspectRatio" attribute of the root {@code <svg>}
  element in the form of an {@link PreserveAspectRatio} object.
  
  @return the preserveAspectRatio setting of the document's root {@code <svg>} element.
  @throws IllegalArgumentException if there is no current SVG document loaded.