code: @SuppressWarnings({"WeakerAccess", "unused"})
     public void  setDocumentPreserveAspectRatio(PreserveAspectRatio preserveAspectRatio)
     {
        if (this.rootElement == null)
           throw new IllegalArgumentException("SVG document is empty");
  
        this.rootElement.preserveAspectRatio = preserveAspectRatio;
     }
docs: Change the document positioning by altering the "preserveAspectRatio"
  attribute of the root {@code <svg>} element.  See the
  documentation for {@link PreserveAspectRatio} for more information
  on how positioning works.
  
  @param preserveAspectRatio the new {@code preserveAspectRatio} setting for the root {@code <svg>} element.
  @throws IllegalArgumentException if there is no current SVG document loaded.