code: public <T> T unmarshal(Class<T> returnType, String postData) throws JsonParseException, JsonMappingException, IOException {
          ObjectMapper objectMapper = getContext(returnType);
          return (objectMapper.readValue(postData, returnType));
      }
docs: Unmarshal the JSON data contained by the string and populate an instance of the provided returnType class.
  
  @param <T> the generics type for the return value
  @param returnType an instance of this type class will be returned
  @param postData a String holding the POST data
  @return an instance of the provided class containing the parsed data from the string
  @throws JsonParseException when an error occurs parsing the provided JSON
  @throws JsonMappingException if a JSON error occurs
  @throws IOException if an error occurs reading the JSON data