title: Write pojo's to parquet file using reflection
body: <p>HI Looking for APIs to write parquest with Pojos that I have.
  I was able to generate avro schema using reflection and then create parquet schema using AvroSchemaConverter. 
  Also i am not able to find a way to convert Pojos to GenericRecords (avro) else I could have been able to use AvroParquetWriter to write out the Pojos into parquet files.
  Any suggestions ?</p>