parquet-hadoop/src/main/java/org/apache/parquet/format/converter/ParquetMetadataConverter.java
MessageType fromParquetSchema(List<SchemaElement> schema, List<ColumnOrder> columnOrders) {
    Iterator<SchemaElement> iterator = schema.iterator();
    SchemaElement root = iterator.next();
    Types.MessageTypeBuilder builder = Types.buildMessage();
    if (root.isSetField_id()) {
      builder.id(root.field_id);
    }
    buildChildren(builder, iterator, root.getNum_children(), columnOrders, 0);
    return builder.named(root.name);
  }
MessageType fromParquetSchema(List<SchemaElement> schema, List<ColumnOrder> columnOrders) {
    Iterator<SchemaElement> iterator = schema.iterator();
    SchemaElement root = iterator.next();
    Types.MessageTypeBuilder builder = Types.buildMessage();
    if (root.isSetField_id()) {
      builder.id(root.field_id);
    }
    buildChildren(builder, iterator, root.getNum_children(), columnOrders, 0);
    return builder.named(root.name);
  }
Visible for testing