Loss of positions information after optimization

[chenqinghaix]

When I add two files to the index library,There are two files in the index library: _0.cfs,_1.cfs.
Here are my two test files：
before_optimize.zip
after_optimize.zip

the properties of the contents field are set to: TERM_VECTOR_WITH_POSITIONS_OFFSETS. After the addition is complete, the position and offset information is normal, but if I use the optimize method to optimizing the index, when complete the positions information in _1.cfs(field contents) have lost.