oracle BPEL Translate activity is sending null instead of JSON empty string

We have requirement to send JSON empty string when xml element as empty value.Can we get expected JSON sample when xml element is empty

Expected JSON Sample:   [{  "values": {  "First_Name": "Test_FirstName",  "Middle_Name": "Test_MiddleName",  "Last_Name": "Test_LastName",  "Title": "Test_Title",  "Birthdate": "2009-08-21",  "Gender": "Male",  "Email_Address": ""   }  }]  

Outcome of Translate Activity : [{  "values": {  "First_Name": "Test_FirstName",  "Middle_Name": "Test_MiddleName",  "Last_Name": "Test_LastName",  "Title": "Test_Title",  "Birthdate": "2009-08-21",  "Gender": "Male",  "Email_Address": null   }  }]

Thanks-Sivateja.