Why doesn't Collapse (Code Folds -> Collapse Fold) work for custom elements in customs.json in Netbeans?

Question

HTML

Started working on an Angular-JS project in Netbeans 8.0.2. For custom directives, so that the IDE does not highlight them as unknown, I add them as custom elements to the file [projectFolder]/nbproject/customs.json by clicking on the corresponding menu drop-down on the hint light bulb. In this case, after adding an element, the ability to collapse the block of this element disappears. Before adding - everything is in order, as with ordinary HTML elements.
Maybe something else needs to be written in the customs.json file ?
File example:

{
    "attributes": {},
    "elements": {
        "fab-form": {
            "attributes": {
                "caption": {}
            }
        }
    }
}

Answer 1

The guess came by itself after writing the question!
It is necessary after adding a new element, if its name consists of different words separated by a hyphen, as in my case, change its name in the file in camelCase notation. Then the element will collapse.

{
    "attributes": {},
    "elements": {
        "fabForm": {
            "attributes": {
                "caption": {}
            }
        }
    }
}