public AssociationList getAssociation(String asId, String asIdType) {
        if (!UtilityMethods.isValidString(asId)) {
            throw new IllegalArgumentException("Id parameter is null");
        }

        Map<String, String> lhtParameters = new HashMap<String, String>();
        if (UtilityMethods.isValidString(asIdType)) {
            lhtParameters.put(PARAM_ID_TYPE, encode(asIdType));
        }

        return get(AssociationList.class, REST_URL_ASSOCIATIONS
                + "/" + encode(asId), lhtParameters);
    }