Seems like a nice change, thanks for working on this Weiwei Yang!
Re Junping's question, the webui is explicitly excluded by our compatibility guidelines, so this is okay to do in branch-2.
I'd actually prefer to keep the Decommissioning header, but can we get a better error message than "No data is available"? e.g. "No nodes are decommisioning"? Otherwise I'm +1.