To allow Lucene to be modularised there are a few preparatory tasks to be completed prior to this being possible. The Java module system requires that jars do not use the same package name in different jars. The lucene-core and lucene-analyzers-common both share the package org.apache.lucene.analysis.standard.
Possible resolutions to this issue are discussed by Uwe on the mailing list here:
About StandardAnalyzer: Unfortunately I aggressively complained a while back when Mike McCandless wanted to move standard analyzer out of the analysis package into core (“for convenience”). This was a bad step, and IMHO we should revert that or completely rename the packages and everything. The problem here is: As the analysis services are only part of lucene-analyzers, we had to leave the factory classes there, but move the implementation classes in core. The package has to be the same. The only way around that is to move the analysis factory framework also to core (I would not be against that). This would include all factory base classes and the service loading stuff. Then we can move standard analyzer and some of the filters/tokenizers including their factories to core an that problem would be solved.
There are two options here, either move factory framework into core or revert StandardAnalyzer back to lucene-analyzers. In the email, the solution lands on reverting back as per the task list:
Add some preparatory issues to cleanup class hierarchy: Move Analysis SPI to core / remove StandardAnalyzer and related classes out of core back to anaysis