title: format inputstream field to json string on java
body: <p>I have a problem when convert a entity to json string in java.
  I have a inputstream field on Customer entity and I want convert Customer entity to json string. All fields of Customer is convert OK, however the value of inputstream field is null after converted.</p>
  
  <p>My code:</p>
  
  <pre><code>protected String convertSettingText(Customer customer) {
      JsonViewJson json = new JsonViewJson();
      String customerJson = json.format(customer);
      return customerJson;
  }
  </code></pre>
  
  <p>How to convert this field (inputstream field) of Customer to json and parse this json to Customer entity?</p>