code: public void execute(
            TransformerImpl transformer)
              throws TransformerException
    {
  
      if (null != m_attributeSetsNames)
      {
        applyAttrSets(transformer, getStylesheetRoot(),
                      m_attributeSetsNames);
      }
   
    }
docs: Copy attributes specified by use-attribute-sets to the result tree.
  Specifying a use-attribute-sets attribute is equivalent to adding
  xsl:attribute elements for each of the attributes in each of the
  named attribute sets to the beginning of the content of the element
  with the use-attribute-sets attribute, in the same order in which
  the names of the attribute sets are specified in the use-attribute-sets
  attribute. It is an error if use of use-attribute-sets attributes
  on xsl:attribute-set elements causes an attribute set to directly
  or indirectly use itself.
  
  @param transformer non-null reference to the the current transform-time state.
  
  @throws TransformerException