title: WSO2 ESB return a string of json structures
body: <p>I'm building an API Resource and return a string of json structures</p>
  
  <p><a href="https://i.stack.imgur.com/eUC1d.png" rel="nofollow noreferrer">enter image description here</a></p>
  
  <p>An error ：
  wso2 com.ctc.wstx.exc.wstxunexpectedcharexception: unexpected character '{' (code 123) in prolog; expected '&lt;' at [row,col {unknown-source}]: [1,1]</p>