The two options TraceYoungGenTime and TraceOldGenTime were not converted to use Unified Logging. Looking at old documentation they were planned to be changed to use the tag-set gc+summary, but it seems to have been forgotten.

Both GenCollectedHeap::print_tracing_info() and ParallelScavengeHeap::print_tracing_info() uses the flags and if enabled print information on tty.

The tag "summary" is not used anywhere else and looking at print_tracing_info for G1 it uses "gc+remset+exit" and "gc+marking" for the information printed so there is no real rule to follow. I suggest using "gc+heap+exit" for this output.