Here it is (value is a String process variable, data is a simple String output parameter of human task, that I want to receive from the form):
<?xml version="1.0" encoding="UTF-8"?>
<bpmn2:definitions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.omg.org/bpmn20" xmlns:bpmn2="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:di="http://www.omg.org/spec/DD/20100524/DI" xmlns:drools="http://www.jboss.org/drools" id="_GGnEYcnUEeGQnP-6F9PmRg" xsi:schemaLocation="http://www.omg.org/spec/BPMN/20100524/MODEL BPMN20.xsd" targetNamespace="http://www.omg.org/bpmn20">
<bpmn2:itemDefinition id="_valueItem" structureRef="String"/>
<bpmn2:itemDefinition id="__A83A6880-44B4-4169-AE8C-70CB94222934_dataOutputItem" structureRef="String"/>
<bpmn2:process id="org.jenkinsci.plugins.jbpm.human" drools:packageName="org.jenkinsci.plugins.jbpm" name="human" isExecutable="true">
<bpmn2:property id="value" itemSubjectRef="_valueItem"/>
<bpmn2:startEvent id="_559F6601-4833-4DDA-B758-8F9D6D7CD42E" drools:bgcolor="#9acd32" name="">
<bpmn2:outgoing>_8691570E-2431-4FA0-8432-8D641D628477</bpmn2:outgoing>
</bpmn2:startEvent>
<bpmn2:userTask id="_A83A6880-44B4-4169-AE8C-70CB94222934" drools:bgcolor="#fafad2" drools:taskName="Evaluation" drools:scriptFormat="http://www.java.com/java" name="Evaluation">
<bpmn2:incoming>_8691570E-2431-4FA0-8432-8D641D628477</bpmn2:incoming>
<bpmn2:outgoing>_04E356CA-786B-48CE-834D-EADB3BA4518C</bpmn2:outgoing>
<bpmn2:ioSpecification id="_GGnrcMnUEeGQnP-6F9PmRg">
<bpmn2:dataInput id="_A83A6880-44B4-4169-AE8C-70CB94222934_TaskNameInput" name="TaskName"/>
<bpmn2:dataInput id="_A83A6880-44B4-4169-AE8C-70CB94222934_SkippableInput" name="Skippable"/>
<bpmn2:dataOutput id="_A83A6880-44B4-4169-AE8C-70CB94222934_dataOutput" drools:dtype="String" itemSubjectRef="__A83A6880-44B4-4169-AE8C-70CB94222934_dataOutputItem" name="data"/>
<bpmn2:inputSet id="_GGnrccnUEeGQnP-6F9PmRg">
<bpmn2:dataInputRefs>_A83A6880-44B4-4169-AE8C-70CB94222934_SkippableInput</bpmn2:dataInputRefs>
<bpmn2:dataInputRefs>_A83A6880-44B4-4169-AE8C-70CB94222934_TaskNameInput</bpmn2:dataInputRefs>
</bpmn2:inputSet>
<bpmn2:outputSet id="_GGnrcsnUEeGQnP-6F9PmRg">
<bpmn2:dataOutputRefs>_A83A6880-44B4-4169-AE8C-70CB94222934_dataOutput</bpmn2:dataOutputRefs>
</bpmn2:outputSet>
</bpmn2:ioSpecification>
<bpmn2:dataInputAssociation id="_GGoSgMnUEeGQnP-6F9PmRg">
<bpmn2:targetRef>_A83A6880-44B4-4169-AE8C-70CB94222934_TaskNameInput</bpmn2:targetRef>
<bpmn2:assignment id="_GGoSgcnUEeGQnP-6F9PmRg">
<bpmn2:from xsi:type="bpmn2:tFormalExpression" id="_GGoSgsnUEeGQnP-6F9PmRg">Evaluation</bpmn2:from>
<bpmn2:to xsi:type="bpmn2:tFormalExpression" id="_GGoSg8nUEeGQnP-6F9PmRg">_A83A6880-44B4-4169-AE8C-70CB94222934_TaskNameInput</bpmn2:to>
</bpmn2:assignment>
</bpmn2:dataInputAssociation>
<bpmn2:dataInputAssociation id="_GGoShMnUEeGQnP-6F9PmRg">
<bpmn2:targetRef>_A83A6880-44B4-4169-AE8C-70CB94222934_SkippableInput</bpmn2:targetRef>
<bpmn2:assignment id="_GGoShcnUEeGQnP-6F9PmRg">
<bpmn2:from xsi:type="bpmn2:tFormalExpression" id="_GGoShsnUEeGQnP-6F9PmRg">false</bpmn2:from>
<bpmn2:to xsi:type="bpmn2:tFormalExpression" id="_GGoSh8nUEeGQnP-6F9PmRg">_A83A6880-44B4-4169-AE8C-70CB94222934_SkippableInput</bpmn2:to>
</bpmn2:assignment>
</bpmn2:dataInputAssociation>
<bpmn2:dataOutputAssociation id="_GGoSiMnUEeGQnP-6F9PmRg">
<bpmn2:sourceRef>_A83A6880-44B4-4169-AE8C-70CB94222934_dataOutput</bpmn2:sourceRef>
<bpmn2:targetRef>value</bpmn2:targetRef>
</bpmn2:dataOutputAssociation>
<bpmn2:potentialOwner id="_GGoSicnUEeGQnP-6F9PmRg">
<bpmn2:resourceAssignmentExpression id="_GGoSisnUEeGQnP-6F9PmRg">
<bpmn2:formalExpression id="_GGoSi8nUEeGQnP-6F9PmRg">admin</bpmn2:formalExpression>
</bpmn2:resourceAssignmentExpression>
</bpmn2:potentialOwner>
</bpmn2:userTask>
<bpmn2:sequenceFlow id="_8691570E-2431-4FA0-8432-8D641D628477" sourceRef="_559F6601-4833-4DDA-B758-8F9D6D7CD42E" targetRef="_A83A6880-44B4-4169-AE8C-70CB94222934"/>
<bpmn2:scriptTask id="_F536F85E-390D-4C9A-A7D2-6DC13CC820CF" drools:bgcolor="#fafad2" name="print output" scriptFormat="http://www.java.com/java">
<bpmn2:incoming>_04E356CA-786B-48CE-834D-EADB3BA4518C</bpmn2:incoming>
<bpmn2:outgoing>_670A74F3-6677-4D74-870A-3904D6E7B5E5</bpmn2:outgoing>
<bpmn2:script><![CDATA[System.out.println("Value from the form: "+kcontext.getVariable("value"));]]></bpmn2:script>
</bpmn2:scriptTask>
<bpmn2:sequenceFlow id="_04E356CA-786B-48CE-834D-EADB3BA4518C" sourceRef="_A83A6880-44B4-4169-AE8C-70CB94222934" targetRef="_F536F85E-390D-4C9A-A7D2-6DC13CC820CF"/>
<bpmn2:sequenceFlow id="_670A74F3-6677-4D74-870A-3904D6E7B5E5" sourceRef="_F536F85E-390D-4C9A-A7D2-6DC13CC820CF" targetRef="_5B509C9E-8AAB-4468-BB62-6D58A799E9EC"/>
<bpmn2:endEvent id="_5B509C9E-8AAB-4468-BB62-6D58A799E9EC" drools:bgcolor="#ff6347" name="">
<bpmn2:incoming>_670A74F3-6677-4D74-870A-3904D6E7B5E5</bpmn2:incoming>
<bpmn2:terminateEventDefinition id="_GGoSjMnUEeGQnP-6F9PmRg"/>
</bpmn2:endEvent>
</bpmn2:process>
<bpmndi:BPMNDiagram id="_GGoSjcnUEeGQnP-6F9PmRg">
<bpmndi:BPMNPlane id="_GGoSjsnUEeGQnP-6F9PmRg" bpmnElement="org.jenkinsci.plugins.jbpm.human">
<bpmndi:BPMNShape id="_GGoSj8nUEeGQnP-6F9PmRg" bpmnElement="_559F6601-4833-4DDA-B758-8F9D6D7CD42E">
<dc:Bounds height="30.0" width="30.0" x="210.0" y="105.0"/>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape id="_GGoSkMnUEeGQnP-6F9PmRg" bpmnElement="_A83A6880-44B4-4169-AE8C-70CB94222934">
<dc:Bounds height="80.0" width="100.0" x="300.0" y="80.0"/>
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="_GGoSkcnUEeGQnP-6F9PmRg" bpmnElement="_8691570E-2431-4FA0-8432-8D641D628477">
<di:waypoint xsi:type="dc:Point" x="225.0" y="120.0"/>
<di:waypoint xsi:type="dc:Point" x="350.0" y="120.0"/>
</bpmndi:BPMNEdge>
<bpmndi:BPMNShape id="_GGoSksnUEeGQnP-6F9PmRg" bpmnElement="_F536F85E-390D-4C9A-A7D2-6DC13CC820CF">
<dc:Bounds height="80.0" width="100.0" x="445.0" y="80.0"/>
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge id="_GGoSk8nUEeGQnP-6F9PmRg" bpmnElement="_04E356CA-786B-48CE-834D-EADB3BA4518C">
<di:waypoint xsi:type="dc:Point" x="350.0" y="120.0"/>
<di:waypoint xsi:type="dc:Point" x="495.0" y="120.0"/>
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge id="_GGoSlMnUEeGQnP-6F9PmRg" bpmnElement="_670A74F3-6677-4D74-870A-3904D6E7B5E5">
<di:waypoint xsi:type="dc:Point" x="495.0" y="120.0"/>
<di:waypoint xsi:type="dc:Point" x="600.0" y="116.0"/>
</bpmndi:BPMNEdge>
<bpmndi:BPMNShape id="_GGoSlcnUEeGQnP-6F9PmRg" bpmnElement="_5B509C9E-8AAB-4468-BB62-6D58A799E9EC">
<dc:Bounds height="28.0" width="28.0" x="586.0" y="102.0"/>
</bpmndi:BPMNShape>
</bpmndi:BPMNPlane>
</bpmndi:BPMNDiagram>
</bpmn2:definitions>