如何在mule esb中使用xpath3表达式替换值

 <babyproducts>
       <products>
           <product1>
               <productid>100</productid>
               <productname>towel</productname>
               <desc>towel</desc>
               <discount>100</discount>
               <validlity>10</validlity>
           </product1>
           <product2>
               <productid>101</productid>
               <productname>pillow</productname>
               <desc>pillow</desc>
               <discount>500</discount>
               <validlity>5</validlity>
           </product2>
       </product>
</babyproducts>
 <babyproducts>
       <products>
           <p