Oracle contract can't add header content

[superboyiii]

Describe the bug
Native Oracle can't add header content.

To Reproduce
Steps to reproduce the behavior:

1. Try a very simple github api https://api.github.com/users/superboyiii.
2. I could use curl https://api.github.com/users/superboyiii or postman.

C:\Users\SPIRIT>curl https://api.github.com/users/superboyiii
{
  "login": "superboyiii",
  "id": 38493437,
  "node_id": "MDQ6VXNlcjM4NDkzNDM3",
  "avatar_url": "https://avatars.githubusercontent.com/u/38493437?v=4",
  "gravatar_id": "",
  "url": "https://api.github.com/users/superboyiii",
  "html_url": "https://github.com/superboyiii",
  "followers_url": "https://api.github.com/users/superboyiii/followers",
  "following_url": "https://api.github.com/users/superboyiii/following{/other_user}",
  "gists_url": "https://api.github.com/users/superboyiii/gists{/gist_id}",
  "starred_url": "https://api.github.com/users/superboyiii/starred{/owner}{/repo}",
  "subscriptions_url": "https://api.github.com/users/superboyiii/subscriptions",
  "organizations_url": "https://api.github.com/users/superboyiii/orgs",
  "repos_url": "https://api.github.com/users/superboyiii/repos",
  "events_url": "https://api.github.com/users/superboyiii/events{/privacy}",
  "received_events_url": "https://api.github.com/users/superboyiii/received_events",
  "type": "User",
  "site_admin": false,
  "name": "Owen Zhang",
  "company": "NEO",
  "blog": "",
  "location": "Shanghai",
  "email": null,
  "hireable": null,
  "bio": null,
  "twitter_username": null,
  "public_repos": 20,
  "public_gists": 0,
  "followers": 22,
  "following": 2,
  "created_at": "2018-04-18T09:43:08Z",
  "updated_at": "2021-04-02T07:12:18Z"
}

3. But I can't get correct response via native oracle contract since user-agent can't be added into header.

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": {
        "txid": "0x2f364a2ebdf9411ceebe6ac0b4b292bec6032bf8d7408502e40ecfea1d73b1e3",
        "executions": [
            {
                "trigger": "Application",
                "vmstate": "FAULT",
                "exception": "An unhandled exception was thrown. Oracle response failure with code 24",
                "gasconsumed": "2416920",
                "stack": [],
                "notifications": [
                    {
                        "contract": "0xfe924b7cfe89ddd271abaf7210a80a7e11178758",
                        "eventname": "OracleResponse",
                        "state": {
                            "type": "Array",
                            "value": [
                                {
                                    "type": "Integer",
                                    "value": "4"
                                },
                                {
                                    "type": "ByteString",
                                    "value": "JHhmRGtMdku9yJUpPdZYQlJ34kUm45Heav95vZuCvzU="
                                }
                            ]
                        }
                    }
                ]
            }
        ]
    }
}

Expected behavior
Header is able to be added to request in native Oracle.

Screenshots
If applicable, add screenshots to help explain your problem.

Platform:

• OS: [any]
• Version [neo latest]

@shargon @erikzhang