code: @Nullable
    public static SchematronOutputType applySchematron (@Nonnull final ISchematronResource aSchematron,
                                                        @Nonnull final Node aNode)
    {
      ValueEnforcer.notNull (aSchematron, "SchematronResource");
      ValueEnforcer.notNull (aNode, "Node");
  
      return applySchematron (aSchematron, new DOMSource (aNode));
    }
docs: Apply the passed schematron on the passed XML node.
  
  @param aSchematron
  The Schematron resource. May not be <code>null</code>.
  @param aNode
  The XML node. May not be <code>null</code>.
  @return <code>null</code> if either the Schematron or the XML could not be
  read.
  @throws IllegalStateException
  if the processing throws an unexpected exception.