FilteredRecordReader skips rows it shouldn't for schema with optional columns

When using UnboundRecordFilter with nested AND/OR filters over OPTIONAL columns, there seems to be a case with a mismatch between the current record's column value and the value read during filtering.

The structure of my filter predicate that results in incorrect filtering is: (x && (y || z))

When I step through it with a debugger I can see that the value being read from the ColumnReader inside my Predicate is different than the value for that row.

Looking deeper there seems to be a buffer with dictionary keys in RunLenghBitPackingHybridDecoder (I am using RLE). There are only two different keys in this array, [0,1], whereas my optional column has three different values, [null,0,1]. If I had a column with values 5,10,10,null,10, and keys 0 -> 5 and 1 -> 10, the buffer would hold 0,1,1,1,0, and in the case that it reads the last row, would return 0 -> 5.

So it seems that nothing is keeping track of where nulls appear.

Hope someone can take a look, as it is a blocker for my project.

**Environment**: Linux, Java7/Java8
**Reporter**: [Steven Mellinger](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=stevemel)
#### Related issues:
- [filter2 API performance regression](https://github.com/apache/parquet-java/issues/1583) (relates to)

_{**Note**: *This issue was originally created as [PARQUET-182](https://issues.apache.org/jira/browse/PARQUET-182). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Inizia tracciando il predicato annidato (x \u0026\u0026 (y || z)) attraverso FilteredRecordReader, UnboundRecordFilter e ColumnReader. Ispeziona RunLenghBitPackingHybridDecoder con una colonna opzionale contenente null, 0 e 1, quindi confronta i valori decodificati con le posizioni delle righe. Il lavoro è completato quando il filtraggio restituisce le righe corrette e la copertura di regressione preserva le posizioni null.

Scritto dal modello di indicizzazione a partire dal testo della issue.