Changes to render full information on alarm tree non-leaf nodes. Also… - #3910

I think this results in much copying and allocation on the heap: every leaf is copied once per layer from the leaf in question to the root.

I think this and the next method (which takes as argument a AlarmTreeItem<?> root) can be combined into a method that takes only a final AlarmTreeItem<?> root as its argument, plus a helper method for traversing the tree, along the following lines:

    protected static Set<AlarmClientLeaf> getLeafItems(final AlarmTreeItem<?> root) {
        return streamLeafItems(root).collect(Collectors.toSet());
    }

    private static Stream<AlarmClientLeaf> streamLeafItems(final AlarmTreeItem<?> alarmTreeItem){
        if (alarmTreeItem instanceof AlarmClientLeaf alarmClientLeaf){
            return Stream.of(alarmClientLeaf);
        }
        else {
            return alarmTreeItem.getChildren().stream().flatMap(child -> streamLeafItems(child));
        }
    }

every leaf is copied once

What does "copied" here mean? No new AlarmClientLeaf objects are created.
But maybe you mean new Set objects are created and AlarmClientLeaf references are copied over?

You are correct: "copying" was inaccurate. I should have written "re-insertion" instead: a reference to every leaf is inserted into a HashSet once per layer from the leaf in question to the root, and each re-insertion (1) hashes the element and (2) allocates a node for the hash set.

The cast can be made type safe:

if(root instanceof AlarmClientLeaf alarmClientLeaf) {

Will udate.