NP because roles is null

{
  "authentication": {
    "class": "solr.BasicAuthPlugin",
    "blockUnknown": true,
    "credentials": {
      "blue": "xxxx"
    }
  },
  "authorization": {
    "class": "solr.RuleBasedAuthorizationPlugin",
    "permissions": [{
      "name": "all",
      "role": "admin"
    }],
    "user-role": {
      "blue": "admin"
    }
  }
}