message: Make HttpAuthentication a polymorphic type.
diff: }
  },
  "ClientCertAuthentication": {
  + "x-ms-discriminator-value": "ClientCertificate",
  "properties": {
  "password": {
  "type": "string",
  ]
  },
  "BasicAuthentication": {
  + "x-ms-discriminator-value": "Basic",
  "properties": {
  "username": {
  "type": "string",
  ]
  },
  "OAuthAuthentication": {
  + "x-ms-discriminator-value": "ActiveDirectoryOAuth",
  "properties": {
  "secret": {
  "type": "string",
  ]
  },
  "HttpAuthentication": {
  + "discriminator": "type",
  + "required": [
  + "type"
  + ],
  "properties": {
  "type": {
  "type": "string",
  