How to get variables from a process and send an email to the specified address?

Question

Java

I have a bmnn-diagram with a user-task and a service-task, a form with mail and letter text fields in Camunda Modeler.

bpmn diagram

<?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_10jhcst"
                  targetNamespace="http://bpmn.io/schema/bpmn" exporter="Camunda Modeler" exporterVersion="4.11.0"
                  modeler:executionPlatform="Camunda Platform" modeler:executionPlatformVersion="7.15.0">
    <bpmn:process id="MailSender" isExecutable="true">
        <bpmn:startEvent id="StartEvent_1">
            <bpmn:outgoing>Flow_0pzjkz9</bpmn:outgoing>
        </bpmn:startEvent>
        <bpmn:sequenceFlow id="Flow_0pzjkz9" sourceRef="StartEvent_1" targetRef="email-request"/>
        <bpmn:endEvent id="Event_0i7bovx">
            <bpmn:incoming>Flow_1cpeti0</bpmn:incoming>
        </bpmn:endEvent>
        <bpmn:sequenceFlow id="Flow_0mr7ogd" sourceRef="email-request" targetRef="sendmail"/>
        <bpmn:userTask id="email-request" name="Выбор email адреса и ввод текста письма"
                       camunda:formKey="camunda-forms:deployment:email-send.form">
            <bpmn:extensionElements>
                <camunda:inputOutput>
                    <camunda:inputParameter name="text">text</camunda:inputParameter>
                    <camunda:inputParameter name="emailAdress">emailAdress</camunda:inputParameter>
                    <camunda:outputParameter name="email">${emailAdress}</camunda:outputParameter>
                    <camunda:outputParameter name="mailText">${text}</camunda:outputParameter>
                </camunda:inputOutput>
            </bpmn:extensionElements>
            <bpmn:incoming>Flow_0pzjkz9</bpmn:incoming>
            <bpmn:outgoing>Flow_0mr7ogd</bpmn:outgoing>
        </bpmn:userTask>
        <bpmn:sequenceFlow id="Flow_1cpeti0" sourceRef="sendmail" targetRef="Event_0i7bovx"/>
        <bpmn:serviceTask id="sendmail" name="Отправка письма" camunda:delegateExpression="${processSendMail}">
            <bpmn:incoming>Flow_0mr7ogd</bpmn:incoming>
            <bpmn:outgoing>Flow_1cpeti0</bpmn:outgoing>
        </bpmn:serviceTask>
    </bpmn:process>
    <bpmndi:BPMNDiagram id="BPMNDiagram_1">
        <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="MailSender">
            <bpmndi:BPMNEdge id="Flow_1cpeti0_di" bpmnElement="Flow_1cpeti0">
                <di:waypoint x="560" y="117"/>
                <di:waypoint x="652" y="117"/>
            </bpmndi:BPMNEdge>
            <bpmndi:BPMNEdge id="Flow_0mr7ogd_di" bpmnElement="Flow_0mr7ogd">
                <di:waypoint x="370" y="117"/>
                <di:waypoint x="460" y="117"/>
            </bpmndi:BPMNEdge>
            <bpmndi:BPMNEdge id="Flow_0pzjkz9_di" bpmnElement="Flow_0pzjkz9">
                <di:waypoint x="188" y="117"/>
                <di:waypoint x="270" y="117"/>
            </bpmndi:BPMNEdge>
            <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">
                <dc:Bounds x="152" y="99" width="36" height="36"/>
                <bpmndi:BPMNLabel>
                    <dc:Bounds x="137" y="142" width="69" height="14"/>
                </bpmndi:BPMNLabel>
            </bpmndi:BPMNShape>
            <bpmndi:BPMNShape id="Event_0i7bovx_di" bpmnElement="Event_0i7bovx">
                <dc:Bounds x="652" y="99" width="36" height="36"/>
                <bpmndi:BPMNLabel>
                    <dc:Bounds x="632" y="142" width="80" height="27"/>
                </bpmndi:BPMNLabel>
            </bpmndi:BPMNShape>
            <bpmndi:BPMNShape id="Activity_0h7rd1s_di" bpmnElement="email-request">
                <dc:Bounds x="270" y="77" width="100" height="80"/>
            </bpmndi:BPMNShape>
            <bpmndi:BPMNShape id="Activity_1orj9ek_di" bpmnElement="sendmail">
                <dc:Bounds x="460" y="77" width="100" height="80"/>
            </bpmndi:BPMNShape>
        </bpmndi:BPMNPlane>
    </bpmndi:BPMNDiagram>
</bpmn:definitions>

The email text has the email-text key.

It is necessary to implement a class in java to receive the user's address and text from the form in order to send an email to the address specified by the user with the specified text.

I do not understand how to write values ​​from the form into variables and process them.