{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "type": "object",
    "properties": {
        "username": {
            "type": "string",
            "maxLength": 20
        },
        "password": {
            "type": "string",
            "maxLength": 20
        }
    },
    "required": [
        "username",
        "password"
    ],
    "additionalProperties": false
}