parquet-hadoop/src/main/java/org/apache/parquet/format/converter/ParquetMetadataConverter.java
List<SchemaElement> toParquetSchema(MessageType schema) {
    List<SchemaElement> result = new ArrayList<SchemaElement>();
    addToList(result, schema);
    return result;
  }
List<SchemaElement> toParquetSchema(MessageType schema) {
    List<SchemaElement> result = new ArrayList<SchemaElement>();
    addToList(result, schema);
    return result;
  }
Visible for testing