### Question:
CompatibleHistorySegment extends CacheColumnSegment implements HistorySegment { @Override public void release() { try { super.release(); } finally { allShowBitMapCache = null; } } CompatibleHistorySegment(IResourceLocation parent, SwiftMetaData meta); @Override ImmutableBitMap getAllShowIndex(); @Override void release();  }### Answer:
@Test public void release() { CompatibleHistorySegment seg = new CompatibleHistorySegment(new ResourceLocation("/"), mock(SwiftMetaData.class)); seg.putRowCount(3); seg.getRowCount(); seg.putAllShowIndex(mock(ImmutableBitMap.class)); seg.getAllShowIndex(); seg.release(); verify(intReader).release(); verify(intWriter).release(); verify(bitmapReader).release(); verify(bitmapWriter).release(); assertNull(Whitebox.getInternalState(seg, "allShowBitMapCache")); }