How to add a JSONField in a behavior?

I need some hints how to implement a behavior with a JSONField.

Via RESTAPI we can add a JSONField of type "dict" with a "json" widget.

curl \
    -s \
    -X POST \
    https://yoursite.org/@types/yourtype \
    -H "Accept: application/json"\
    -H "Content-Type: application/json" \
    --data-raw '{
        "description": "My Json field",
        "factory": "JSONField", 
        "title": "json", 
        "type": "dict",
        "widget": "json"
        }' \
    --user ${USER}

But I cannot find any documentation neither for type "dict" nor for widget "json".

In following docs I was not able to find any hints.

Don't understand what you are trying to accomplish...but why isn't it sufficient to store a JSON string as Text?

What I need: I have different Dexterity types that have a JSON-field. I don't want to repeat code and add that field to every type. I think this could be best accomplished with a behaviour.

Why a Text field is not optimal: The text field simple stores a string and makes no checks at all. The JSONField checks if the JSON (i.e. the dict) is "well-formed"

I need a way to create a JSONfield and its widget in a behavior.

Any field can have its own validators.
Deriving your own JSONField from Text does not seem to be so complicated.

Cant you just add a JSON field in Dexterity Editor and then copy the XML (syntax) you get to your behaviour (field) ?

The JSONField is not a IText-ish field. Actually it is a IDict field.
What I'm searching for is the json widget for a dict field.

With other words: is there a documentation or a link to source code that explains the options and the meaning of the widget-key called by plone.restapi @types (see example in my question)?

Finally I found it:

The JSONField

The JSONWidget

And:

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