private Map<?, ?> convertJsonToMap(final String jsonString) {
    Map<String, String> map;

    // convert JSON string to Map
    try {
      map = objectMapper.readValue(jsonString, new TypeReference<HashMap<String, String>>() {});
    } catch (JsonParseException e) {
      throw new MalformedJsonException(
          "Bind params specified as JSON document in the request is incorrect!", e);
    } catch (JsonMappingException e) {
      throw new MalformedJsonException(
          "Server unable to process bind params specified as JSON document in the request!", e);
    } catch (IOException e) {
      throw new GemfireRestException("Server has encountered error while process this request!", e);
    }
    return map;
  }
AbstractBaseController class contains common functionalities required for other controllers.

@since GemFire 8.0
geode-web-api/src/main/java/org/apache/geode/rest/internal/web/controllers/AbstractBaseController.java