All muxed account IDs fields should be strings

[bartekn]

What version are you using?

2.4.1

What did you do?

All IDs of muxed accounts returned by Horizon API should be of type string because they represent uint64 variable. Rendering a JSON number can cause issues in JS.

https://horizon-testnet.stellar.org/transactions/905fd0d6412aab6ddcef0dcdd21c0ea6934e88856f79679fc4c80fe0f8213437/operations

{
  "_links": {
    "self": {
      "href": "https://horizon-testnet.stellar.org/transactions/905fd0d6412aab6ddcef0dcdd21c0ea6934e88856f79679fc4c80fe0f8213437/operations?cursor=\u0026limit=10\u0026order=asc"
    },
    "next": {
      "href": "https://horizon-testnet.stellar.org/transactions/905fd0d6412aab6ddcef0dcdd21c0ea6934e88856f79679fc4c80fe0f8213437/operations?cursor=455665965346817\u0026limit=10\u0026order=asc"
    },
    "prev": {
      "href": "https://horizon-testnet.stellar.org/transactions/905fd0d6412aab6ddcef0dcdd21c0ea6934e88856f79679fc4c80fe0f8213437/operations?cursor=455665965346817\u0026limit=10\u0026order=desc"
    }
  },
  "_embedded": {
    "records": [
      {
        "_links": {
          "self": {
            "href": "https://horizon-testnet.stellar.org/operations/455665965346817"
          },
          "transaction": {
            "href": "https://horizon-testnet.stellar.org/transactions/905fd0d6412aab6ddcef0dcdd21c0ea6934e88856f79679fc4c80fe0f8213437"
          },
          "effects": {
            "href": "https://horizon-testnet.stellar.org/operations/455665965346817/effects"
          },
          "succeeds": {
            "href": "https://horizon-testnet.stellar.org/effects?order=desc\u0026cursor=455665965346817"
          },
          "precedes": {
            "href": "https://horizon-testnet.stellar.org/effects?order=asc\u0026cursor=455665965346817"
          }
        },
        "id": "455665965346817",
        "paging_token": "455665965346817",
        "transaction_successful": true,
        "source_account": "GAGYDQGN5FXRAWGDBD4EG5LRVGEM2APXIIU7LXRO6SIQVPQIHOR4KCBE",
        "type": "payment",
        "type_i": 1,
        "created_at": "2021-06-22T20:09:49Z",
        "transaction_hash": "905fd0d6412aab6ddcef0dcdd21c0ea6934e88856f79679fc4c80fe0f8213437",
        "asset_type": "native",
        "from": "GAGYDQGN5FXRAWGDBD4EG5LRVGEM2APXIIU7LXRO6SIQVPQIHOR4KCBE",
        "to": "GBJR3ISFRWXWGGMTAAGKCF43NPFII55YRKMGPNCO6EH2WO6MSN2ER5WA",
        "to_muxed": "MBJR3ISFRWXWGGMTAAGKCF43NPFII55YRKMGPNCO6EH2WO6MSN2EQAAAAAB2JLEZFLMGM",
        "to_muxed_id": 15647676714,
        "amount": "900.0000000"
      }
    ]
  }
}

What did you expect to see?

        "to_muxed_id": "15647676714",

What did you see instead?

        "to_muxed_id": 15647676714,

[bartekn]

Fixed in #3716.