presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/RaptorMetadata.java/RaptorMetadata/getBucketColumnHandles
class RaptorMetadata:    private static List<RaptorColumnHandle> getBucketColumnHandles(List<String> bucketColumns, Map<String, RaptorColumnHandle> columnHandleMap)
    {
        ImmutableList.Builder<RaptorColumnHandle> columnHandles = ImmutableList.builder();
        for (String column : bucketColumns) {
            if (!columnHandleMap.containsKey(column)) {
                throw new PrestoException(NOT_FOUND, "Bucketing column does not exist: " + column);
            }
            columnHandles.add(columnHandleMap.get(column));
        }
        return columnHandles.build();
    }