Mongoose LoginSchema with jwt token-store

const LoginSchema = new Schema({
    username: {
        type: String,
        unique: true
    },
    email: {
        type: String,
        unique: true
    },
    password: {
        type: String,
        minlength: 8
    },
    tokens: [
        {
            tokenString: {
                type: String
            },
            tokenType: {
                type: String,
                enum: ['access', 'refresh']
            },
            isBlacklisted: {
                type: Boolean,
                default: false
            }
        }
    ]
});