How to use spring beans in expressions in Activiti (ServiceTask)?

Question

Business Informatics

Hello. Can't use beans in expressions in Activiti (in ServiceTask). He writes that he does not see this bin.
Excerpt from pom by version:

<springframework.version>5.0.2.RELEASE</springframework.version>
        <springframework.boot>2.0.4.RELEASE</springframework.boot>
        <activiti.version>6.0.0</activiti.version>

Beans are defined by annotations over classes.
Excerpt from the bpmn schema file:

<serviceTask id="SendStatus104" name="Формирование и отправка статуса" activiti:expression="${sendService.sendStatusCode(104)}">
      <documentation>Формирование и отправка статуса</documentation>
    </serviceTask>

Class declaration:

@Service("sendService")
public class SendServiceImpl implements SendService {
//some code
}