presto-orc/src/main/java/io/prestosql/orc/StripeReader.java/StripeReader/isDictionary
class StripeReader:    private static boolean isDictionary(Stream stream, ColumnEncodingKind columnEncoding)
    {
        return stream.getStreamKind() == DICTIONARY_DATA || (stream.getStreamKind() == LENGTH && (columnEncoding == DICTIONARY || columnEncoding == DICTIONARY_V2));
    }