JAXB/Jackson handle list of objects

I am trying to map a JSON representation of a list into java classes. I generate my Java using "XSD to Java" and "WADL to Java".

I have the following representation:

JSON:

[
{
    "type": "deployment_unit",
    "id": 28,
    "name": "Tomcat-8080-localhost",
    "state": "stopped",
    "url": "http://localhost:8080/"
},
{
    "type": "deployment_unit",
    "id": 4,
    "name": "Tomcat-Production",
    "state": "stopped",
    "url": "foobar"
}

]

I get the JSON object from a web service. The request is correct.

I am not free to modify the XML/JSON representation. I can only modify the XSD files to generate Java. So I have defined a "deployment unit" complex type in xsd. I have also defined a type for "deployment units". this type is just representing a list of "deployment unit" objects.

<xsd:complexType name="DeploymentUnit">
    <xsd:sequence>
        <xsd:element name="id" type="xsd:int" />
        <xsd:element name="name" type="xsd:string" />
         <xsd:element name="state" type="DeploymentUnitState" />
        <xsd:element name="url" type="xsd:string" />
    </xsd:sequence>
</xsd:complexType>

<xsd:complexType name="DeploymentUnits">
    <xsd:sequence>
        <xsd:element name="deployment_unit" type="DeploymentUnit" maxOccurs="unbounded" />
        </xsd:sequence>
</xsd:complexType>

I have the following class generated in Java:

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "DeploymentUnits", propOrder = {"deploymentUnit"})
@XmlRootElement(name = "deployment_units")

public class DeploymentUnits extends AbstractEntityBase
{
@XmlElement(name = "deployment_unit", required = true)
protected List<DeploymentUnit> deploymentUnit;

public List<DeploymentUnit> getDeploymentUnit() {
    if (deploymentUnit == null) {
        deploymentUnit = new ArrayList<DeploymentUnit>();
    }
    return this.deploymentUnit;
}

}

My problem is: I always get an empty List after the unmarshalling. JAXB/Jackson seems to don't map the elements correctly and I don't find why.

Note: I have no problem to map only one deployment unit in my java object.

    DeploymentUnits units = proxy.getDeploymentUnitResource().search();
    System.out.println("Empty list ? -> " + units.getDeploymentUnit().isEmpty()); (always return true :( )

I would like to get a List containing the 2 elements of the JSON array.

Any idea ?