presto-iceberg/src/main/java/io/prestosql/plugin/iceberg/PartitionTransforms.java/PartitionTransforms/bucketVarchar
class PartitionTransforms:    private static Block bucketVarchar(Block block, int count)
    {
        return bucketBlock(block, count, position -> bucketHash(VARCHAR.getSlice(block, position)));
    }