docs: public static String getNonEmptyStringParam(JSONObject params, String paramName) throws ApiException {
  		if (!params.containsKey(paramName)) {
  			throw new ApiException(Type.MISSING_PARAMETER, paramName);
  		}
  		String value = params.getString(paramName);
  		if (value == null || value.isEmpty()) {
  			throw new ApiException(Type.MISSING_PARAMETER, paramName);
  		}
  		return value;
  	}