JSON Schema Property 'voices'

"voices": {
    "type": "array",
    "description": "Voices the extension can synthesize.",
    "minItems": 1,
    "uniqueItems": true,
    "items": {
        "type": "object",
        "additionalProperties": false,
        "properties": {
            "voice_name": {
                "type": "string",
                "description": "Identifies the name of the voice and the engine used."
            },
            "lang": {
                "type": "string",
                "description": "Almost always, a voice can synthesize speech in just a single language. When an engine supports more than one language, it can easily register a separate voice for each language."
            },
            "gender": {
                "type": "string",
                "description": "If your voice corresponds to a male or female voice, you can use this parameter to help clients choose the most appropriate voice for their application."
            },
            "event_types": {
                "type": "array",
                "description": "Events sent to update the client on the progress of speech synthesis.",
                "minItems": 1,
                "uniqueItems": true,
                "items": {
                    "type": "string",
                    "description": "",
                    "enum": [
                        "start",
                        "word",
                        "sentence",
                        "marker",
                        "end",
                        "error"
                    ]
                }
            }
        },
        "required": [
            "voice_name",
            "event_types"
        ]
    }
}

• /properties/tts_engine