presto-orc/src/main/java/io/prestosql/orc/writer/StructColumnWriter.java/StructColumnWriter/getNestedColumnWriters
class StructColumnWriter:    @Override
    public List<ColumnWriter> getNestedColumnWriters()
    {
        ImmutableList.Builder<ColumnWriter> nestedColumnWriters = ImmutableList.builder();
        for (ColumnWriter structField : structFields) {
            nestedColumnWriters
                    .add(structField)
                    .addAll(structField.getNestedColumnWriters());
        }
        return nestedColumnWriters.build();
    }