code: function defaultAuthProviders(bson) {
    return {
      mongocr: new MongoCR(bson),
      x509: new X509(bson),
      plain: new Plain(bson),
      gssapi: new GSSAPI(bson),
      sspi: new SSPI(bson),
      'scram-sha-1': new ScramSHA1(bson),
      'scram-sha-256': new ScramSHA256(bson)
    };
  }
docs: Returns the default authentication providers.
  
  @param {BSON} bson Bson definition
  @returns {Object} a mapping of auth names to auth types