WordPress/wp-includes/blocks/spacer/block.json

{
	"apiVersion": 2,
	"name": "core/spacer",
	"category": "design",
	"attributes": {
		"height": {
			"type": "number",
			"default": 100
		}
	},
	"supports": {
		"anchor": true
	},
	"editorStyle": "wp-block-spacer-editor",
	"style": "wp-block-spacer"
}