### Question:
CacheColumnSegment extends BaseSegment { @Override public void release() { try { super.release(); } finally { SegmentUtils.releaseHisColumn(columns.values()); } } CacheColumnSegment(IResourceLocation location, SwiftMetaData meta); @Override Column<T> getColumn(ColumnKey key); @Override void release();  }### Answer:
@Test public void release() throws Exception { SwiftMetaData meta = mock(SwiftMetaData.class); when(meta.getColumnId("c")).thenReturn("cId"); CacheColumnSegment seg = new CacheColumnSegment(new ResourceLocation("/"), meta); seg.getColumn(new ColumnKey("cId")); seg.release(); Map<ColumnKey, Column<?>> columns = Whitebox.getInternalState(seg, "columns"); verifyStatic(SegmentUtils.class); SegmentUtils.releaseHisColumn(columns.values()); }