### Question:
NullValueVectorReaderImpl implements NullValueVectorReader { public boolean isNull(int docId) { return _nullBitmap.contains(docId); } NullValueVectorReaderImpl(PinotDataBuffer dataBuffer); boolean isNull(int docId); @Override ImmutableRoaringBitmap getNullBitmap();  }### Answer:
@Test public void testNullValueVectorReader() throws IOException { Assert.assertEquals(TEMP_DIR.list().length, 1); File nullValueFile = new File(TEMP_DIR, TEMP_DIR.list()[0]); PinotDataBuffer buffer = PinotDataBuffer.loadBigEndianFile(nullValueFile); NullValueVectorReader reader = new NullValueVectorReaderImpl(buffer); for (int i = 0; i < 100; i++) { Assert.assertTrue(reader.isNull(i)); } }