{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "title": "Addition error",
    "description": "Error message from addition service",
    "type": "object",
    "properties": {
        "error": {
            "type": "string"
        }
    },
    "additionalProperties": false,
    "required": [
        "error"
    ]
}