In applications that should optimise for minor garbage collection (which is most of the cloud-based one in my experience), it is useful to set the -Xmn to fix how much memory can be allocated in the heap for young generation. This parameter usually makes sense a fraction of the total heap memory, so that allocating more memory to the surrounding container lets the memory allocated to young generation expand linearly with the total memory available to the heap.
This release introduces the --heap-young-generation-ratio, with default .3, that sets the -Xmn as a fraction of the memory allocated to the heap. If -Xmn is specifically passed as a JVM option, --heap-young-generation-ratio is ignored.