{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "type": "object",
    "properties": {
        "tags": {
            "type": "array",
            "minItems": 2,
            "maxItems": 4,
            "items": {
                "enum": [
                    "Open Source",
                    "Java",
                    "JavaScript",
                    "JSON",
                    "REST"
                ]
            }
        }
    },
    "additionalProperties": false,
    "required": [
        "tags"
    ]
}