code: @Override
      public UnlinkIdentityResult unlinkIdentity(UnlinkIdentityRequest request) {
          request = beforeClientExecution(request);
          return executeUnlinkIdentity(request);
      }
docs: <p>
  Unlinks a federated identity from an existing account. Unlinked logins will be considered new identities next
  time they are seen. Removing the last linked login will make this identity inaccessible.
  </p>
  <p>
  This is a public API. You do not need any credentials to call this API.
  </p>
  
  @param unlinkIdentityRequest
  Input to the UnlinkIdentity action.
  @return Result of the UnlinkIdentity operation returned by the service.
  @throws InvalidParameterException
  Thrown for missing or bad input parameter(s).
  @throws ResourceNotFoundException
  Thrown when the requested resource (for example, a dataset or record) does not exist.
  @throws NotAuthorizedException
  Thrown when a user is not authorized to access the requested resource.
  @throws ResourceConflictException
  Thrown when a user tries to use a login which is already linked to another account.
  @throws TooManyRequestsException
  Thrown when a request is throttled.
  @throws InternalErrorException
  Thrown when the service encounters an error during processing the request.
  @throws ExternalServiceException
  An exception thrown when a dependent service such as Facebook or Twitter is not responding
  @sample AmazonCognitoIdentity.UnlinkIdentity
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/cognito-identity-2014-06-30/UnlinkIdentity"
  target="_top">AWS API Documentation</a>