@Tim
There is definitely only 1 version of parent nad child class.
Peter Johnson wrote:Are all of these class in the same project, or are some of them in a separate project? If a separate project, are you using a SNAPSHOT version? If so, then each time you build that other project you will get a different JAR file (snapshots include a timestamp in the jar file name), and m2e has to update Eclipse to reference the correct JAR file for your project. (This is all a guess...)
These classes are in different modules, but under one project. Each module is versioned as 1.0, so they are not SNAPSHOTs. But your point seems to me very likely as possible problem.
By the way, I found another way which relatively solve this problem - removing generics:
But changing code with removing generics I don't consider as a good solution...
However, we redefined generics in parent class and also in child classes and now code works. But I don't certainly found out why this problem occured in former code and is still weird for me.