{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "additionalProperties": false,
    "type": "object",
    "properties": {
        "expression": {
            "title": "Expression",
            "description": "What to evaluate; JSON paths are allowed, wrapped in {{this.is.a.path}}",
            "type": "string",
            "minLength": 1
        }
    },
    "required": [
        "expression"
    ]
}