agent/acs/handler/refresh_credentials_handler.go
func (refreshHandler *refreshCredentialsHandler) handlerFunc() func(message *ecsacs.IAMRoleCredentialsMessage) {
	// return a function that just enqueues IAMRoleCredentials messages into the message buffer
	return func(message *ecsacs.IAMRoleCredentialsMessage) {
		refreshHandler.messageBuffer <- message
	}
}
func (refreshHandler *refreshCredentialsHandler) handlerFunc() func(message *ecsacs.IAMRoleCredentialsMessage) {
	// return a function that just enqueues IAMRoleCredentials messages into the message buffer
	return func(message *ecsacs.IAMRoleCredentialsMessage) {
		refreshHandler.messageBuffer <- message
	}
}
// handlerFunc returns the request handler function for the ecsacs.IAMRoleCredentialsMessage