<?xml version="1.0"?>

<xs:schema version="1.0"
           xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:ns="http://www.stackoverflow.com/users"
           elementFormDefault="qualified"
           targetNamespace="http://www.stackoverflow.com/users">
    <xs:element name="users" type="ns:Users"/>
    
    <xs:complexType name="Users">
        <xs:sequence>
            <xs:element type="ns:User" name="user" minOccurs="0" maxOccurs="unbounded"/>
        </xs:sequence>
    </xs:complexType>
    
    <xs:complexType name="User">
        <xs:attribute name="name" use="required" type="xs:string"/>
        <xs:attribute name="reputation" use="required">
            <xs:simpleType>
                <xs:restriction base="xs:int">
                    <xs:minInclusive value="1"/>
                </xs:restriction>
            </xs:simpleType>
        </xs:attribute>
    </xs:complexType>
</xs:schema>

xjc schema.xsd

package com.stackoverflow.users;

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.XmlType;

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "Users", propOrder = {
    "user"
})
public class Users {

    protected List<User> user;

    public List<User> getUser() {
        if (user == null) {
            user = new ArrayList<User>();
        }
        return this.user;
    }

}

package com.stackoverflow.users;

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

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "User")
public class User {

    @XmlAttribute(name = "name", required = true)
    protected String name;
    @XmlAttribute(name = "reputation", required = true)
    protected int reputation;

    public String getName() {
        return name;
    }

    public void setName(String value) {
        this.name = value;
    }

    public int getReputation() {
        return reputation;
    }

    public void setReputation(int value) {
        this.reputation = value;
    }

}

package com.stackoverflow.users;

import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.XmlElementDecl;
import javax.xml.bind.annotation.XmlRegistry;
import javax.xml.namespace.QName;

@XmlRegistry
public class ObjectFactory {

    private final static QName _Users_QNAME = new QName("http://www.stackoverflow.com/users", "users");

    public ObjectFactory() {
    }

    public Users createUsers() {
        return new Users();
    }

    public User createUser() {
        return new User();
    }

    @XmlElementDecl(namespace = "http://www.stackoverflow.com/users", name = "users")
    public JAXBElement<Users> createUsers(Users value) {
        return new JAXBElement<Users>(_Users_QNAME, Users.class, null, value);
    }

}

@javax.xml.bind.annotation.XmlSchema(namespace = "http://www.stackoverflow.com/users", elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED)
package com.stackoverflow.users;