{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "title": "Constraint",
    "description": "Constraint to the parameter.",
    "type": "array",
    "items": {
        "type": "object",
        "required": [
            "allowed_pattern",
            "description"
        ],
        "properties": {
            "allowed_pattern": {
                "description": "A regular expression pattern.",
                "type": "string",
                "default": "null"
            },
            "description": {
                "description": "A human readable description of the constraint.",
                "type": "string",
                "default": "null"
            }
        }
    }
}