[PATCH] Add method for simpler SequenceCommands

[taylor.smock]

Use case:
You build a series of commands, each of which may have a series of subcommands. It would be nice if, instead of creating a SequenceCommand for a single command, if there was a way to just get the original command.

In the MapWithAI plugin, I've added logic that is essentially if (commands.size() == 1) return commands.get(0); else return new SequenceCommand(desc, commands);.

The attached patch adds two new static methods to SequenceCommand, both of which take the same arguments as a new object would. They return the singular command, or a sequence command.

It also makes a modification to the DeleteCommand.delete method so that if no ChangeCommand is created, it just returns a DeleteCommand.

[simon04]

Sometimes, wrapping even just one command is intended for a more descriptive command name, e.g., org.openstreetmap.josm.actions.CombineWayAction.

I'm unsure whether having just one occurrence in JOSM core justifies this addition… Maybe wrapIfNeeded would be a more precise function name?

[taylor.smock]

Possibly. I think I just modified one command in core where it made sense (to me). I do like wrapIfNeeded over createSimplifiedSequenceCommand. It is shorter and clearer.

In one of my plugins, I have a bunch of if (list.size() == 1) return list.get(0); else if (!list.isEmpty()) return new SequenceCommand(list, message); else return null;. This is mostly so I don't have trees of SequenceCommands when debugging. I kind of figured that other people might find it useful in core/other plugins.

[taylor.smock]

createSimplifiedSequenceCommand -> wrapIfNeeded

[simon04]

In 16573/josm:

fix #19056 - Add SequenceCommand.wrapIfNeeded (patch by taylor.smock)

[simon04]

In 16574/josm:

see #19056 - Add SequenceCommandTest.testWrapIfNeeded