This sample code shows how to:
▸ Use the JAXB maven plugin to generate Java classes from the XML schemas.
▸ Customize JAXB Bindings to reference existing classes.

|+ mtitek-jaxb-maven-plugin-samples
   |+ src
      |+ main
         |+ java
            |+ mtitek.jaxb.samples.payload
               |+ Payload.java
            |+ mtitek.jaxb.samples.payload.data
               |+ DataType.java
         |+ resources
            |+ payload.xsd
            |+ payload.xjb
            |+ payloadData.xsd
            |+ payloadData.xjb
   |+ pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>mtitek.jaxb.samples</groupId>
    <artifactId>mtitek-jaxb-samples</artifactId>
    <version>1.0.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <build>
        <plugins>
            <plugin>
                <groupId>org.jvnet.jaxb2.maven2</groupId>
                <artifactId>maven-jaxb2-plugin</artifactId>
                <version>0.13.1</version>

                <executions>
                    <execution>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                    </execution>
                </executions>

                <configuration>
                    <args>
                        <arg>-Xsetters</arg>
                    </args>

                    <plugins>
                        <plugin>
                            <groupId>org.jvnet.jaxb2_commons</groupId>
                            <artifactId>jaxb2-basics</artifactId>
                            <version>1.11.1</version>
                        </plugin>
                    </plugins>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema elementFormDefault="qualified"
    attributeFormDefault="unqualified"
    targetNamespace="http://samples.jaxb.mtitek/payload"
    xmlns="http://samples.jaxb.mtitek/payload"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:jaxb="http://java.sun.com/xml/ns/jaxb"
    jaxb:version="2.1">

    <xs:element name="payload">
        <xs:complexType>
            <xs:sequence>
                <xs:element name="id" type="xs:string" />

                <xs:element name="code" type="xs:string" />

                <xs:element name="parameter" type="parameterType" minOccurs="0" maxOccurs="unbounded" />

                <xs:element name="payloadData" type="payloadDataType" minOccurs="0" />
            </xs:sequence>
        </xs:complexType>
    </xs:element>

    <xs:complexType name="parameterType">
        <xs:all>
            <xs:element name="name" type="xs:string" />
            <xs:element name="value" type="xs:string" />
        </xs:all>

        <xs:attribute name="id" type="xs:string" />
    </xs:complexType>

    <xs:complexType name="payloadDataType">
        <xs:sequence>
            <xs:any minOccurs="0" maxOccurs="unbounded" namespace="##other" processContents="strict">
                <xs:annotation>
                    <xs:appinfo>
                        <jaxb:property name="values" />
                    </xs:appinfo>
                </xs:annotation>
            </xs:any>
        </xs:sequence>
    </xs:complexType>
</xs:schema>

<jxb:bindings version="1.0"
    xmlns:jxb="http://java.sun.com/xml/ns/jaxb"
    jaxb:version="2.1"
    xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <jxb:bindings node="//xs:schema//xs:element[@name='payload']" schemaLocation="./payload.xsd">
        <jxb:class ref="mtitek.jaxb.samples.payload.Payload" />
    </jxb:bindings>
</jxb:bindings>

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<xs:schema elementFormDefault="qualified"
    attributeFormDefault="unqualified"
    targetNamespace="http://samples.jaxb.mtitek/payload/data"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:ns1="http://samples.jaxb.mtitek/payload/data">

    <xs:element name="data" type="ns1:dataType" />

    <xs:complexType name="dataType">
        <xs:sequence>
            <xs:element name="value" type="xs:anyType" />
        </xs:sequence>

        <xs:attribute name="id" type="xs:string" />
    </xs:complexType>

    <xs:complexType name="textDataType">
        <xs:sequence>
            <xs:element name="value" type="xs:string" />
        </xs:sequence>

        <xs:attribute name="id" type="xs:string" />
    </xs:complexType>

    <xs:complexType name="dateDataType">
        <xs:sequence>
            <xs:element name="value" type="xs:dateTime" />
        </xs:sequence>

        <xs:attribute name="id" type="xs:string" />
    </xs:complexType>
</xs:schema>

<jxb:bindings version="1.0"
    xmlns:jxb="http://java.sun.com/xml/ns/jaxb"
    jaxb:version="2.1"
    xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <jxb:bindings node="//xs:schema//xs:complexType[@name='dataType']" schemaLocation="./payloadData.xsd">
        <jxb:class ref="mtitek.jaxb.samples.payload.data.DataType" />
    </jxb:bindings>
</jxb:bindings>

package mtitek.jaxb.samples.payload;

import java.util.ArrayList;
import java.util.List;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = { "id", "code", "parameters", "payloadData" })
@XmlRootElement(name = "payload")
public class Payload {
    @XmlElement(required = true)
    private String id;

    @XmlElement(required = true)
    private String code;

    @XmlElement(name = "parameter")
    private final List<ParameterType> parameters = new ArrayList<>();

    private PayloadDataType payloadData;

    public String getId() {
        return id;
    }

    public void setId(String value) {
        this.id = value;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String value) {
        this.code = value;
    }

    public List<ParameterType> getParameters() {
        List<ParameterType> copyParameters = new ArrayList<ParameterType>();
        copyParameters.addAll(this.parameters);
        return copyParameters;
    }

    public void setParameters(final List<ParameterType> parameters) {
        this.parameters.clear();

        if (parameters != null) {
            this.parameters.addAll(parameters);
        }
    }

    public PayloadDataType getPayloadData() {
        return payloadData;
    }

    public void setPayloadData(PayloadDataType value) {
        this.payloadData = value;
    }

    @Override
    public String toString() {
        return "Payload [id=" + id + ", code=" + code + "]";
    }
}

package mtitek.jaxb.samples.payload.data;

import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlRootElement(name = "data")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "dataType", propOrder = { "value" })
public class DataType {
    @XmlAttribute(name = "id")
    protected String id;

    @XmlElement(required = true)
    protected Object value;

    public String getId() {
        return id;
    }

    public void setId(String value) {
        this.id = value;
    }

    public Object getValue() {
        return value;
    }

    public void setValue(Object value) {
        this.value = value;
    }

    @Override
    public String toString() {
        return "DataType [id=" + id + ", value=" + value + "]";
    }
}

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<payload xmlns="http://samples.jaxb.mtitek/payload"
    xmlns:ns1="http://samples.jaxb.mtitek/payload/data"
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://samples.jaxb.mtitek/payload payload.xsd
        http://samples.jaxb.mtitek/payload/data payloadData.xsd">
    <id>123</id>
    <code>xyz</code>

    <parameter id="11">
        <name>bar</name>
        <value>foo</value>
    </parameter>

    <parameter id="22">
        <value>ti</value>
        <name>ta</name>
    </parameter>

    <payloadData>
        <ns1:data id="3">
            <ns1:value id="31" xsi:type="ns1:textDataType">
                <ns1:value>bbb</ns1:value>
            </ns1:value>
        </ns1:data>

        <ns1:data id="4">
            <ns1:value id="41" xsi:type="ns1:dateDataType">
                <ns1:value>2017-11-16T17:49:50.816Z</ns1:value>
            </ns1:value>
        </ns1:data>
    </payloadData>
</payload>