这两个版本都是bug修正版本
重要改进内容：
- An increased maximum number of unique terms in each index segment.
- Fixed experimental CustomScoreQuery to
respect per-segment search. This introduced an API change!
- Important fixes to IndexWriter: a
commit() thread-safety issue, lost document deletes in near real-time
indexing.
- Bugfixes for Contrib's Analyzers package.
- Restoration of some public methods that were lost during deprecation
removal (3.0.1 only).
- The new Attribute-based TokenStream
API now works correctly with different class loaders.
详情请看：
http://lucene.apache.org/java/3_0_1/changes/Changes.html
http://lucene.apache.org/java/2_9_2/changes/Changes.html
强烈建议升级！！！
下载地址：http://www.apache.org/dyn/closer.cgi/lucene/java/
