Como criar uma matriz de matrizes de esquema de objetos em Mongoose.js

const cellSchema = new mongoose.Schema({
    type: String,
    count: Number
});

const matrixSchema = new mongoose.Schema({
    matrix: [[cellSchema]]
});

const Matrix = mongoose.model('Matrix', matrixSchema);

const newMatrix = new Matrix({
    matrix: [
        [{ type: 'xyz', count: 10 }, { type: 'ABC', count: 20 }],
        [{ type: 'pqr', count: 10 }]]
});
newMatrix.save();