[json] Improve combining schemas not working with 'additionalProperties: false' #20193
Description
When combining schemas such as when multiple extensions have schemas for package.json we use 'allOf' to combine.
This works well as long as none of the schemas uses additionalProperties: false.
{
"allOf": [
{
"type": "object",
"additionalProperties": false,
"properties": {
"bar": {
"description": "bar"
},
"foo": {
"description": "foo" }
}
},
{
"type": "object",
"additionalProperties": false,
"properties": {
"xoo": {
"description": "xoo"
}
}
}
]
}