private static <K, V> void addResult(final Map<K, List<V>> results, final K key, final Object value) {
        if (value == null) {
            return;
        }
        val currentValue = results.computeIfAbsent(key, __ -> new ArrayList<>());
        if (value instanceof List) {
            currentValue.addAll((Collection<? extends V>) value);
        } else {
            currentValue.add((V) value);
        }
    }
{@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