According to IntelliJ
such references can cause JVM-level deadlocks in multithreaded environment, when one thread tries to load the superclass and another thread tries to load the subclass at the same time
- Referencing subclass
StaticFunction from superclass Function initializer might lead to class loading deadlock
- Referencing subclass
ByDepth from superclass TreePruner initializer might lead to class loading deadlock