code: @Override
      public ActivateUserResult activateUser(ActivateUserRequest request) {
          request = beforeClientExecution(request);
          return executeActivateUser(request);
      }
docs: <p>
  Activates the specified user. Only active users can access Amazon WorkDocs.
  </p>
  
  @param activateUserRequest
  @return Result of the ActivateUser operation returned by the service.
  @throws EntityNotExistsException
  The resource does not exist.
  @throws UnauthorizedOperationException
  The operation is not permitted.
  @throws UnauthorizedResourceAccessException
  The caller does not have access to perform the action on the resource.
  @throws FailedDependencyException
  The AWS Directory Service cannot reach an on-premises instance. Or a dependency under the control of the
  organization is failing, such as a connected Active Directory.
  @throws ServiceUnavailableException
  One or more of the dependencies is unavailable.
  @sample AmazonWorkDocs.ActivateUser
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/workdocs-2016-05-01/ActivateUser" target="_top">AWS API
  Documentation</a>