private String getUserName(final String queryUserName, final Map<String, Object> queryResult, final String userNameAttribute) {
        if (this.isUserNameAttributeConfigured() && queryResult.containsKey(userNameAttribute)) {
            return queryResult.get(userNameAttribute).toString();
        }
        if (queryUserName != null) {
            return queryUserName;
        }
        if (queryResult.containsKey(userNameAttribute)) {
            return queryResult.get(userNameAttribute).toString();
        }
        throw new IllegalArgumentException("No username column named " + userNameAttribute + " exists in result set");
    }
{@link Map} of columns from a name column to value columns.
Keys are Strings, Values are Strings or Set of Strings.
support/cas-server-support-jdbc-authentication/src/main/java/org/apereo/cas/jdbc/MultiRowJdbcPersonAttributeDao.java