title: Postgresql use json_populate_recordset can not use empty value
body: <p>When I use this sql to test json_populate_recordset ,there is no error:</p>
  
  <pre><code>select 'name',(json_populate_recordset(null::"trn_rebatesys_20mstcontractdetail",'[
          {
              "s_line_no":1,
              "departmentcd":30,
              "catagorycd":2,
              "jan":"",
              "seriescd":"",
              "f_exclude":0
          }
  
      ]')).s_line_no,(json_populate_recordset(null::"trn_rebatesys_20mstcontractdetail",'[
          {
              "s_line_no":1,
              "departmentcd":30,
              "catagorycd":2,
              "jan":"",
              "seriescd":"",
              "f_exclude":0
          }
  
      ]')).departmentcd
  </code></pre>
  
  <p>Result:
  <a href="https://i.stack.imgur.com/DZ2jT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/DZ2jT.png" alt="enter image description here"></a></p>
  
  <p>But when I change the second<code>"departmentcd":30</code> to <code>"departmentcd":""</code>,
  the error message said <code>Error: type integer input syntax is invalid: ""</code>,how to fix it?How do deal empty string?</p>