有如下数组

[{
    "id": "49088",
    "user_id": "8733",
    "user_name": "echo",
    "order_id": "23749",
    "title":"demo-title1"
},{
    "id": "49089",
    "user_id": "8733",
    "user_name": "echo",
    "order_id": "23749",
    "title":"demo-title2"
},{
    "id": "49090",
    "user_id": "8733",
    "user_name": "echo",
    "order_id": "23750",
    "title":"demo-title3"
},{
    "id": "49091",
    "user_id": "8733",
    "user_name": "echo",
    "order_id": "23751",
    "title":"demo-title4"
},{
    "id": "49092",
    "user_id": "8733",
    "user_name": "echo",
    "order_id": "23751",
    "title":"demo-title5"
},{
    "id": "49093",
    "user_id": "8733",
    "user_name": "echo",
    "order_id": "23752",
    "title":"demo-title6"
}]

需转换成这种格式

[
    [{
        "id": "49088",
        "user_id": "8733",
        "user_name": "echo",
        "order_id": "23749",
        "title": "demo-title1"
    }, {
        "id": "49089",
        "user_id": "8733",
        "user_name": "echo",
        "order_id": "23749",
        "title": "demo-title2"
    }], {
        "id": "49090",
        "user_id": "8733",
        "user_name": "echo",
        "order_id": "23750",
        "title": "demo-title3"
    },
    [{
        "id": "49091",
        "user_id": "8733",
        "user_name": "echo",
        "order_id": "23751",
        "title": "demo-title4"
    }, {
        "id": "49092",
        "user_id": "8733",
        "user_name": "echo",
        "order_id": "23751",
        "title": "demo-title5"
    }], {
        "id": "49093",
        "user_id": "8733",
        "user_name": "echo",
        "order_id": "23752",
        "title": "demo-title6"
    }
]

即把原数组有相同order_id的元素合并成新数组添加到原数组里面。请高手指点迷津。