fix #862: Made start form key retrieval more robust

integration/camunda-bpm/taskpool-collector/src/main/kotlin/io/holunda/polyflow/taskpool/collector/process/definition/ProcessDefinitionService.kt

@@ -50,7 +50,15 @@ class ProcessDefinitionService(
       this.processDefinitions.clear()
     }
     this.processDefinitions.addAll(newDefinitions)
-    return newDefinitions.map { it.asCommand(applicationName = collectorProperties.applicationName, formKey = formService.getStartFormKey(it.id)) }
+    return newDefinitions.map { it.asCommand(applicationName = collectorProperties.applicationName, formKey = getStartFormKey(it, formService)) }
+  }
+
+  private fun getStartFormKey(processDefinitionEntity: ProcessDefinitionEntity, formService: FormService): String? {
+    return if (processDefinitionEntity.hasStartFormKey) {
+      formService.getStartFormKey(processDefinitionEntity.id)
+    } else {
+      null
+    }
   }
 
   /**

integration/camunda-bpm/taskpool-collector/src/test/kotlin/io/holunda/polyflow/taskpool/itest/tx/ProcessDefinitionServiceITest.kt

@@ -86,6 +86,52 @@ class ProcessDefinitionServiceITest {
     assertThat(definitions[0].candidateStarterGroups).containsExactlyElementsOf(listOf("muppetshow"))
   }
 
+  @Test
+  fun `should not deliver process starter if no start form is available`() {
+
+    val processId = "my-id"
+    val startEventId = "start"
+    val modelInstance = Bpmn
+      .createExecutableProcess(processId)
+      .startEvent(startEventId)
+      .endEvent("end")
+      .done().apply {
+        getModelElementById<ModelElementInstance>(processId).setAttributeValue("name", "My Process")
+        getModelElementById<ModelElementInstance>(processId).setAttributeValueNs(NS_CAMUNDA, "candidateStarterGroups", "muppetshow")
+      }
+
+    repositoryService
+      .createDeployment()
+      .addModelInstance("process-without-start-form.bpmn", modelInstance)
+      .deploy()
+
+
+    val definitions = processDefinitionService.getProcessDefinitions(processEngine.processEngineConfiguration as ProcessEngineConfigurationImpl)
+
+    assertThat(definitions).isNotEmpty
+    assertThat(definitions[0].processName).isEqualTo("My Process")
+    assertThat(definitions[0].processDefinitionKey).isEqualTo("my-id")
+    assertThat(definitions[0].processDefinitionVersion).isEqualTo(1)
+    assertThat(definitions[0].formKey).isNull()
+    assertThat(definitions[0].candidateStarterGroups).containsExactlyElementsOf(listOf("muppetshow"))
+  }
+
+  @Test
+  fun `should not deliver process starter if only two message start events are available`() {
+    repositoryService
+      .createDeployment()
+      .addClasspathResource("itest/message_start_event.bpmn")
+      .deploy()
+
+    val definitions = processDefinitionService.getProcessDefinitions(processEngine.processEngineConfiguration as ProcessEngineConfigurationImpl)
+
+    assertThat(definitions).isNotEmpty
+    assertThat(definitions[0].processName).isEqualTo("My Process")
+    assertThat(definitions[0].processDefinitionKey).isEqualTo("my-id")
+    assertThat(definitions[0].processDefinitionVersion).isEqualTo(1)
+    assertThat(definitions[0].formKey).isNull()
+  }
+
   /**
    * Internal test application.
    */

integration/camunda-bpm/taskpool-collector/src/test/resources/itest/message_start_event.bpmn

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<bpmn:definitions xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:camunda="http://camunda.org/schema/1.0/bpmn" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:modeler="http://camunda.org/schema/modeler/1.0" id="Definitions_0xgy7na" targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="5.10.0" modeler:executionPlatform="Camunda Platform" modeler:executionPlatformVersion="7.19.0">
+  <bpmn:process id="my-id" name="My Process" isExecutable="true" camunda:historyTimeToLive="0">
+    <bpmn:endEvent id="Event_0b6e9a9">
+      <bpmn:incoming>Flow_0rqm55e</bpmn:incoming>
+      <bpmn:incoming>Flow_1k4xpiz</bpmn:incoming>
+    </bpmn:endEvent>
+    <bpmn:sequenceFlow id="Flow_0rqm55e" sourceRef="StartEvent_1" targetRef="Event_0b6e9a9" />
+    <bpmn:sequenceFlow id="Flow_1k4xpiz" sourceRef="Event_0tam437" targetRef="Event_0b6e9a9" />
+    <bpmn:startEvent id="StartEvent_1">
+      <bpmn:outgoing>Flow_0rqm55e</bpmn:outgoing>
+      <bpmn:messageEventDefinition id="MessageEventDefinition_1nlj1v7" messageRef="Message_2t2ssos" />
+    </bpmn:startEvent>
+    <bpmn:startEvent id="Event_0tam437">
+      <bpmn:outgoing>Flow_1k4xpiz</bpmn:outgoing>
+      <bpmn:messageEventDefinition id="MessageEventDefinition_1ft2zip" messageRef="Message_22tfs8s" />
+    </bpmn:startEvent>
+  </bpmn:process>
+  <bpmn:message id="Message_2t2ssos" name="start_message" />
+  <bpmn:message id="Message_22tfs8s" name="another_message" />
+  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
+    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="my-id">
+      <bpmndi:BPMNShape id="Event_0b6e9a9_di" bpmnElement="Event_0b6e9a9">
+        <dc:Bounds x="272" y="79" width="36" height="36" />
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNShape id="Event_0qcrckj_di" bpmnElement="StartEvent_1">
+        <dc:Bounds x="179" y="79" width="36" height="36" />
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNShape id="Event_02sa6i2_di" bpmnElement="Event_0tam437">
+        <dc:Bounds x="179" y="152" width="36" height="36" />
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNEdge id="Flow_0rqm55e_di" bpmnElement="Flow_0rqm55e">
+        <di:waypoint x="215" y="97" />
+        <di:waypoint x="272" y="97" />
+      </bpmndi:BPMNEdge>
+      <bpmndi:BPMNEdge id="Flow_1k4xpiz_di" bpmnElement="Flow_1k4xpiz">
+        <di:waypoint x="215" y="170" />
+        <di:waypoint x="244" y="170" />
+        <di:waypoint x="244" y="97" />
+        <di:waypoint x="272" y="97" />
+      </bpmndi:BPMNEdge>
+    </bpmndi:BPMNPlane>
+  </bpmndi:BPMNDiagram>
+</bpmn:definitions>