Considerable time passed after java version 9 was released. And as it turned out, my plugin for vim stopped working with this java version.
The issue with my plugin was in that all java base classes now keeping in modules under the jmod directory in jdk root. But in past releases it was located in libs directory using simple jar files.
Another one, in «Java9» extensions and enviroment variable
java.ext.dirs have been removed, that led to NPE.
Solution turned up to be simple. In archive scanning process, besides jar and zip, I added jmod files as well.
And I added check for null of