Calling Universe::heap()->print_on_error() gets dispatched to the most specific implementation, which for some GCs is their own implementation instead of the default in CollectedHeap. Each GC-specific implementation calls back to CollectedHeap::print_on_error(), which then dispatches back into the specific implementation of print_on(). This is kind of awkward and creates a call-chain that's not straightforward to wrap your head around, jumping back and forth via CollectedHeap and the specific implementation.

To make the call-chain cleaner, I propose making print_on_error() a pure virtual method in CollectedHeap, forcing each implementation of CollectedHeap to implement it on their own, making the call-chain stay inside the specific implementation. In addition, I also suggest we remove print_extended_on() and leave that to the GCs that want such functionality.

Removing the common print_on_error() also means that GCs that do not print anything interesting for their barrier set (ZGC & Shenandoah) can omit printing barrier set information.

To make print_on_error() consistent with print_on(), I also suggest we move the printing of "Heap:" to the caller of print_on_error() (only inside vmError.cpp). This is a trivial change for all GCs except ZGC, which requires some restructuring in its error printing.