Add differentiation of nested records with the same name

Hello,

While reading back a Parquet file produced with Spark, it appears the schema produced by Parquet-Avro is not valid.

I consider the simple following piece of code:

```Java

ParquetReader reader =

             AvroParquetReader.builder(new org.apache.hadoop.fs.Path(path.toUri())).build();

             System.out.println(reader.read().getSchema());

```

I get a stack lile:

```Java

Exception in thread "main" +org.apache.avro.SchemaParseException+: Can't redefine: value

       at org.apache.avro.Schema$Names.put(+Schema.java:1128+)

       at org.apache.avro.Schema$NamedSchema.writeNameRef(+Schema.java:562+)

       at org.apache.avro.Schema$RecordSchema.toJson(+Schema.java:690+)

       at org.apache.avro.Schema$UnionSchema.toJson(+Schema.java:882+)

       at org.apache.avro.Schema$MapSchema.toJson(+Schema.java:833+)

       at org.apache.avro.Schema$UnionSchema.toJson(+Schema.java:882+)

       at org.apache.avro.Schema$RecordSchema.fieldsToJson(+Schema.java:716+)

       at org.apache.avro.Schema$RecordSchema.toJson(+Schema.java:701+)

       at org.apache.avro.Schema.toString(+Schema.java:324+)

       at org.apache.avro.Schema.toString(+Schema.java:314+)

```

 

The issue seems the same as the one reported in:

 

It have been fixed in Spark-avro within:

In our case, the parquet schema looks like:

```Java

message spark_schema {
optional group calculatedobjectinfomap (MAP) {
repeated group key_value {
required binary key (UTF8);
optional group value {
optional int64 calcobjid;
optional int64 calcobjparentid;
optional binary portfolioname (UTF8);
optional binary portfolioscheme (UTF8);
optional binary calcobjtype (UTF8);
optional binary calcobjmnemonic (UTF8);
optional binary calcobinstrumentype (UTF8);
optional int64 calcobjectqty;
optional binary calcobjboid (UTF8);
optional binary analyticalfoldermnemonic (UTF8);
optional binary calculatedidentifier (UTF8);
optional binary calcobjlevel (UTF8);
optional binary calcobjboidscheme (UTF8);
}
}
}
optional group riskfactorinfomap (MAP) {
repeated group key_value {
required binary key (UTF8);
optional group value {
optional binary riskfactorname (UTF8);
optional binary riskfactortype (UTF8);
optional binary riskfactorrole (UTF8);
}
}
}
}

```
We indeed have 2 Map field with a value fields named 'value'. The name 'value' is defaulted in org.apache.spark.sql.types.MapType.

The fix seems not trivial given current parquet-avro code then I doubt I will be able to craft a valid PR without directions.

Thanks,

**Reporter**: [Benoit Lacelle](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=blasd)

_{**Note**: *This issue was originally created as [PARQUET-1202](https://issues.apache.org/jira/browse/PARQUET-1202). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

AvroParquetReader.builder と、示された Parquet スキーマの読み取り時に関係するスキーマ変換パスから始め、MapType がデフォルト値の名前をどのように提供しているかを調べます。ネストされたマップの例で失敗を再現し、spark-avro の pull request 73 で参照されているアプローチと比較します。ネストされたレコード名が繰り返されるスキーマが Avro の "Can't redefine" 例外なしでシリアライズされれば完了です。

索引モデルが issue の本文から書いたものです。