@Override
    public OutputStream getBody() {
      return outputStream;
    }
The CustomMappingJackson2HttpMessageConverter class...

@see org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
@since GemFire 0.0.1
geode-web-management/src/main/java/org/apache/geode/management/internal/rest/converter/CustomMappingJackson2HttpMessageConverter.java