Also, justifying it by security is not convincing. Encapsulation / decoupling and security are different things. The internals can anyways be accessed through c

Also, justifying it by security is not convincing. Encapsulation / decoupling and security are different things. The internals can anyways be accessed through core-dumps, /dev/mem, side-channels, etc. Yes, the strong encapsulation of JDK impl classes can create some inconveniences to an attacker. But I don't feel it's valuable enough to justify luck of access to the internals.