Error in reading a list type data in hive which was generated through pig

ArrayWritableGroupConverter in Parquet-Hive binding expects that any array field contains either 1 or 2 fields. However, the schema which PigSchemaConverter generates, doesn't honour this condition. It can be reproduced through following code

```
MessageType messageType = new PigSchemaConverter().convert(ThriftToPig.toSchema(Requestlist.class));
DataWritableGroupConverter converter = new DataWritableGroupConverter(messageType, messageType);
```

Requestlist is a thrift class
```
struct Request {
1: required string id,
2: i64 time,
3: required string source
}

struct Requestlist {
1: optional list requests
}
```

**Environment**: Parquet-Pig - 1.3.2
Hive - 0.13.1
Elephant-Bird - 4.4
**Reporter**: [Abhishek Agarwal](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=abhishek.agarwal) / @abhishekagarwal87

_{**Note**: *This issue was originally created as [PARQUET-53](https://issues.apache.org/jira/browse/PARQUET-53). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

先从 Parquet-Hive 绑定中的 ArrayWritableGroupConverter 和 PigSchemaConverter 开始，然后使用报告中的 Requestlist schema 和 DataWritableGroupConverter snippet 重现该问题。跟踪生成的列表 schema，并将其与 converter 对一个或两个字段的预期进行对照；完成标准是生成的 schema 可以在不出现此转换错误的情况下读取。

由索引模型根据 Issue 内容生成。