client must honor the protocol default specified by the provider

the provider advertises what protocols and ports it supports.

the client should use the first one listed. in this example, only "tcp" is listed, and so it should use that:

{
  "gateways": [
    {
      "capabilities": {
        "adblock": false,
        "filter_dns": false,
        "limited": false,
        "ports": [
          "443"
        ],
        "protocols": [
          "tcp"
        ],
        "transport": [
          "openvpn"
        ],
        "user_ips": false
      },
      "host": "millipede.demo.bitmask.net",
      "ip_address": "198.252.153.84",
      "location": "seattle__wa"
    },
    {
      "capabilities": {
        "adblock": false,
        "filter_dns": false,
        "limited": false,
        "ports": [
          "443"
        ],
        "protocols": [
          "tcp"
        ],
        "transport": [
          "openvpn"
        ],
        "user_ips": false
      },
      "host": "otter.demo.bitmask.net",
      "ip_address": "46.165.242.169",
      "location": "frankfurt"
    }
  ],
  "locations": {
    "frankfurt": {
      "country_code": "DE",
      "hemisphere": "N",
      "name": "Frankfurt",
      "timezone": "+1"
    },
    "seattle__wa": {
      "country_code": "US",
      "hemisphere": "N",
      "name": "Seattle, WA",
      "timezone": "-7"
    }
  },
  "openvpn_configuration": {
    "auth": "SHA1",
    "cipher": "AES-128-CBC",
    "keepalive": "10 30",
    "tls-cipher": "DHE-RSA-AES128-SHA",
    "tun-ipv6": true
  },
  "serial": 1,
  "version": 1
}