default boolean isColumnSortable(FacesContext context, UIColumn column) {
        Map<String, SortMeta> sortBy = getSortByAsMap();
        if (sortBy.containsKey(column.getColumnKey())) {
            return true;
        }

        // lazy init - happens in cases where the column is initially not rendered
        SortMeta s = SortMeta.of(context, getVar(), column);
        if (s != null) {
            sortBy.put(s.getColumnKey(), s);
        }
        setSortByAsMap(sortBy);

        return s != null;
    }
Returns actives sort meta. See {@link SortMeta#compareTo(SortMeta)}
@return map with {@link SortMeta#getField()} as key and {@link SortMeta} as value
primefaces/src/main/java/org/primefaces/component/api/UITable.java