Android RestTemplate: How to assign the JSON Message converter

[OneWorld123]

Thats my approach so far:

     
//relevant imports:
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJacksonHttpMessageConverter; //shipped w/ RestTemplate

The part w/ the error:

List<HttpMessageConverter<?>> mc = restTemplate.getMessageConverters();
      mc.add(new MappingJacksonHttpMessageConverter()); //throws VerifyError
      restTemplate.setMessageConverters(mc);

Thats the Error I am getting:

java.lang.VerifyError: org.springframework.http.converter.json.MappingJacksonHttpMessageConverter