Add stub module for Java 8 types

[odrotbohm]

To be able to compile code against JDK 8 types without having to use a JDK 8 to compile we need to add a library providing type mocks of JDK 8 types. Using JDK 8 directly currently causes a lot of pain in Spring Data builds as it requires to run with Spring 4 (which is a non-option for the Dijkstra release train as we have to preserve 3.2 compatibility) and breaks tests here and there as downstream libraries sometimes aren't compatible with JDK 8 bytecode (ASM I am looking at you!).