mandatory status of avro columns ignored

Avro spec schema [resolution rules ](https://avro.apache.org/docs/1.7.7/spec.html#schema_record) say:
"if the reader's record schema has a field with no default value, and writer's schema does not have a field with the same name, an error is signalled."

I can't find the implementation of this aspect in parquet.avro and indeed observe this rule seemingly ignored. I am using 1.6.0 because that's what we can get off maven.

My writer's schema:
```Java
{
"type" : "record",
"name" : "SampleSchema_v1",
"namespace" : "com.xxxx.spark",
"fields" : [ {
"name" : "stringField",
"type" : "string",
"doc" : "Sample string field"
},{
"name" : "longField",
"type" : "long",
"doc" : "Sample long field"
} ],
"doc:" : "A sample/test schema"
}
```

My reader schema:
```Java
{
"type" : "record",
"name" : "SampleSchema_newDefaultlessCol",
"namespace" : "com.xxxx.spark",
"fields" : [ {
"name" : "stringField",
"type" : "string",
"doc" : "Sample string field"
},{
"name" : "longField",
"type" : "long",
"doc" : "Sample long field"
},{
"name" : "mandatoryIntField",
"type" : "int",
"doc" : "Sample mandatory! int field"
}],
"doc:" : "v1 + one extra column that has no default"
}
```
This is my test case:
```Java
"accept new column w/o a default [schema-evolution, undesired]" in new MockAvroParquetGrid {
//TODO: the behaviour this test case exercises is UNDESIRED, i.e.: a new column with no default value should
//TODO: Ticket to track this: https://jira.xxxx.io/browse/ADR-610
//constitute an incompatible schema break, instead, this thing uses 0 for the default
val inputSampleRecordsV1 = Seq(new SampleSchema_v1(s"string", 1))
dao.writeParquet[SampleSchema_v1](
SparkBase.sc.parallelize(inputSampleRecordsV1),
SampleSchema_v1.SCHEMA$,
parquetFolder
)

dao
.readParquet[SampleSchema_newDefaultlessCol](parquetFolder, SampleSchema_newDefaultlessCol.SCHEMA$)
.collect().toSeq.head
.getMandatoryIntField must equalTo(0) //TODO: zero is an unwelcome guess
}
```
This is the implementation of writeParquet and readParquet
```Java
def writeParquet[C](source: RDD[C], schema: org.apache.avro.Schema, dstPath: String)
(implicit ctag: ClassTag[C]): Unit = {
val hadoopJob = Job.getInstance()
ParquetOutputFormat.setWriteSupportClass(hadoopJob, classOf[AvroWriteSupport])
ParquetOutputFormat.setCompression(hadoopJob, CompressionCodecName.GZIP)
AvroWriteSupport.setSchema(hadoopJob.getConfiguration, schema)

new PairRDDFunctions[Void,C](
source.map(sourceRecord => (null, sourceRecord))
).saveAsNewAPIHadoopFile(
bucketDAO.uri(dstPath),
classOf[Void], //K
ctag.runtimeClass.asInstanceOf[Class[C]], //V
classOf[AvroParquetOutputFormat],
hadoopJob.getConfiguration
)
}

def readParquet[C](srcPath: String, schema: org.apache.avro.Schema)(implicit ctag: ClassTag[C]): RDD[C] = {
val hadoopJob = Job.getInstance()
ParquetInputFormat.setReadSupportClass(hadoopJob, classOf[AvroReadSupport[C]])
AvroReadSupport.setAvroReadSchema(hadoopJob.getConfiguration, schema)
sc.newAPIHadoopFile(
bucketDAO.uri(srcPath),
classOf[ParquetInputFormat[C]],
classOf[Void], //K
ctag.runtimeClass.asInstanceOf[Class[C]], //V
hadoopJob.getConfiguration
).map { _._2 }
}
```
We use avro-tools to generate java classes from our avro schemas.
java -jar /path/to/avro-tools-1.8.0.jar compile schema

The test case harvests zeroes as values of mandatoryIntField

Naively, I see a problem in the [indexed revord converter](https://git-wip-us.apache.org/repos/asf?p=parquet-mr.git;a=blob;f=parquet-avro/src/main/java/org/apache/parquet/avro/AvroIndexedRecordConverter.java;h=06c66d692571da08298ae1da4f9967446c4864ee;hb=HEAD#l105) in that it cheerfully accepts a condition doomed to fail. The condition being: the reader schema has a column with no default value that is absent in the writer schema.

I am writing predominantly to confirm my diagnosis and to get the intell on why is it implemented the way it is. Is it fixable (or other depend on it as on a feature)? Can people think of a workaround?

**Reporter**: [Remek Zajac](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=remek.zajac@gmail.com)

_{**Note**: *This issue was originally created as [PARQUET-577](https://issues.apache.org/jira/browse/PARQUET-577). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Start with the linked AvroIndexedRecordConverter implementation and the MockAvroParquetGrid test case using the supplied writer and reader schemas. Reproduce the read of a missing mandatoryIntField, then trace how its absent value becomes zero; done means the incompatible schema is rejected instead of silently producing a value.

Written by the indexing model from the issue text.