Validation set: ‘flowable-executable-process‘ | Problem: ‘flowable-servicetask-missing-implementatio

org.flowable.common.engine.api.FlowableException: Errors while parsing:
[Validation set: 'flowable-executable-process' | Problem: 'flowable-servicetask-missing-implementation'] : One of the attributes 'class', 'delegateExpression', 'type', 'operation', or 'expression' is mandatory on serviceTask. - [Extra info : processDefinitionId = myProcess | processDefinitionName = My process |  | id = servicetask4 |  | activityName = D | ] ( line: 12, column: 45)

    at org.flowable.engine.impl.bpmn.parser.BpmnParse.execute(BpmnParse.java:177)
    at org.flowable.engine.impl.bpmn.deployer.ParsedDeploymentBuilder.createBpmnParseFromResource(ParsedDeploymentBuilder.java:97)
    at org.flowable.engine.impl.bpmn.deployer.ParsedDeploymentBuilder.build(ParsedDeploymentBuilder.java:55)
    at org.flowable.engine.impl.bpmn.deployer.BpmnDeployer.deploy(BpmnDeployer.java:78)
    at org.flowable.engine.impl.persistence.deploy.DeploymentManager.deploy(DeploymentManager.java:62)
    at org.flowable.engine.impl.cmd.DeployCmd.executeDeploy(DeployCmd.java:135)
    at org.flowable.engine.impl.cmd.DeployCmd.execute(DeployCmd.java:70)
    at org.flowable.engine.impl.cmd.DeployCmd.execute(DeployCmd.java:45)
    at org.flowable.engine.impl.interceptor.CommandInvoker$1.run(CommandInvoker.java:59)
    at org.flowable.engine.impl.interceptor.CommandInvoker.executeOperation(CommandInvoker.java:107)
    at org.flowable.engine.impl.interceptor.CommandInvoker.executeOperations(CommandInvoker.java:81)
    at org.flowable.engine.impl.interceptor.CommandInvoker.execute(CommandInvoker.java:64)
    at org.flowable.engine.impl.interceptor.BpmnOverrideContextInterceptor.execute(BpmnOverrideContextInterceptor.java:26)
    at org.flowable.common.engine.impl.interceptor.TransactionContextInterceptor.execute(TransactionContextInterceptor.java:53)
    at org.flowable.common.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:83)
    at org.flowable.common.spring.SpringTransactionInterceptor.lambda$execute$0(SpringTransactionInterceptor.java:57)
    at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:140)
    at org.flowable.common.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:57)
    at org.flowable.common.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:35)
    at org.flowable.common.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:56)
    at org.flowable.common.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:51)
    at org.flowable.engine.impl.RepositoryServiceImpl.deploy(RepositoryServiceImpl.java:99)
    at org.flowable.engine.impl.repository.DeploymentBuilderImpl.deploy(DeploymentBuilderImpl.java:206)
    at com.dream21th.flowable.bpmn.task.serviceTask.ServiceTaskDemo.deploy(ServiceTaskDemo.java:75)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

This mistake is because ServiceTask To configure the business processing class for a task, you can set the following three properties

activiti:class="com.dream21th.flowable.bpmn.task.serviceTask.ADelegete"

activiti:expression="${bDelegete.execute(execution)}"

activiti:delegateExpression="${cDelegate}">

 <serviceTask id="servicetask4" name="D">
    
 </serviceTask>

Configure on the following page