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.
  

See this page for details how to use JAXB to marshal and unmarshal Java objects and XML documents:
JAXB Marshalling/Unmarshalling

<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.bindings</groupId>
    <artifactId>mtitek-jaxb-bindings</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>0.14.0</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 attributeFormDefault="unqualified"
    elementFormDefault="qualified" targetNamespace="http://bindings.jaxb.mtitek/payload"
    xmlns="http://bindings.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="parameters" type="payloadParameters"
                    minOccurs="0" maxOccurs="1" />
            </xs:sequence>
        </xs:complexType>
    </xs:element>

    <xs:complexType name="payloadParameters">
        <xs:sequence>
            <xs:element name="parameter" type="payloadParameter"
                minOccurs="1" maxOccurs="unbounded" />
        </xs:sequence>
    </xs:complexType>

    <xs:complexType name="payloadParameter">
        <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:schema>

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

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

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

package mtitek.jaxb.bindings.payload;

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;

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

    @XmlElement(name = "code", required = true)
    private String code;

    private PayloadParameters parameters;

    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 PayloadParameters getParameters() {
        return parameters;
    }

    public void setParameters(PayloadParameters parameters) {
        this.parameters = parameters;
    }

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

<jxb:bindings version="1.0" xmlns:jxb="http://java.sun.com/xml/ns/jaxb"
    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.bindings.payload.Payload" />
    </jxb:bindings>
</jxb:bindings>