Groovy: как проверить, есть ли у экземпляра JAXB вложенное свойство и присутствует или нет значение

Question

Ниже приведен XML-код, проанализированный как экземпляр JAXB

<client>
      <cl_id>111871</cl_id>
      <cl_lf_id>115124</cl_lf_id>
      <cl_name>0118</cl_name>
      <cl_address>
        <address_1>Test Corp</address_1>
        <address_2>200 GRANVILLE STREET</address_2>
        <address_3></address_3>
        <city>Austin</city>
        <state_province>TX</state_province>
        <zip_postal_code>77777</zip_postal_code>
        <country>USA</country>
        <phone>111-224-3858</phone>
        <file_item_nbr>5</file_item_nbr>
      </cl_address>
      <file_item_nbr>6</file_item_nbr>      
</client>

Ниже приведен XSD для `Client

<xsd:complexType name="client">
    <xsd:sequence>
        <xsd:element name="cl_id" type="string20" minOccurs="0" maxOccurs="1"/>
        <xsd:element name="cl_lf_id" type="string20" minOccurs="1" maxOccurs="1"/>
        <xsd:element name="cl_name" type="string120" minOccurs="1" maxOccurs="1"/>
        <xsd:element name="cl_address" type="address_info" minOccurs="1" maxOccurs="1"/>
        <xsd:element name="client_contact" type="contact_info" minOccurs="0" maxOccurs="1"/>
        <xsd:element name="cl_tax_id" type="string20" minOccurs="0" maxOccurs="1"/>
        <xsd:element name="file_item_nbr" type="xsd:nonNegativeInteger" minOccurs="1" maxOccurs="1"/>
        <xsd:element name="extend_header" type="extend_header" minOccurs="0" maxOccurs="1"/>
        <xsd:element name="invoice" type="invoice" minOccurs="1" maxOccurs="unbounded"/>
    </xsd:sequence>
</xsd:complexType>

Ниже приведены JAXB Pojos для вышеуказанного xml

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "client", propOrder = {
    "clId",
    "clLfId",
    "clName",
    "clAddress",
    "clientContact",
    "clTaxId",
    "fileItemNbr",
    "extendHeader",    
})
public class Client {

    @XmlElement(name = "cl_id")
    protected String clId;
    @XmlElement(name = "cl_lf_id", required = true)
    protected String clLfId;
    @XmlElement(name = "cl_name", required = true)
    protected String clName;
    @XmlElement(name = "cl_address", required = true)
    protected AddressInfo clAddress;
    @XmlElement(name = "client_contact")
    protected ContactInfo clientContact;
    @XmlElement(name = "cl_tax_id")
    protected String clTaxId;
    @XmlElement(name = "file_item_nbr", required = true)
    @XmlSchemaType(name = "nonNegativeInteger")
    protected BigInteger fileItemNbr;
    @XmlElement(name = "extend_header")
    protected ExtendHeader extendHeader;
}

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "address_info", propOrder = {
    "address1",
    "address2",
    "address3",
    "city",
    "stateProvince",
    "zipPostalCode",
    "country",
    "phone",
    "fax",
    "fileItemNbr"
})
public class AddressInfo {

    @XmlElement(name = "address_1", required = true)
    protected String address1;
    @XmlElement(name = "address_2")
    protected String address2;
    @XmlElement(name = "address_3")
    protected String address3;
    @XmlElement(required = true)
    protected String city;
    @XmlElement(name = "state_province", required = true)
    protected String stateProvince;
    @XmlElement(name = "zip_postal_code", required = true)
    protected String zipPostalCode;
    @XmlElement(required = true)
    protected String country;
    @XmlElement(required = true)
    protected String phone;
    protected String fax;
    @XmlElement(name = "file_item_nbr", required = true)
    @XmlSchemaType(name = "nonNegativeInteger")
    protected BigInteger fileItemNbr;
}

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "contact_info", propOrder = {
    "contactLname",
    "contactFname",
    "contactId",
    "contactPhone",
    "contactFax",
    "contactEmail",
    "fileItemNbr"
})
public class ContactInfo {
    @XmlElement(name = "contact_lname", required = true)
    protected String contactLname;
    @XmlElement(name = "contact_fname", required = true)
    protected String contactFname;
    @XmlElement(name = "contact_id")
    protected String contactId;
    @XmlElement(name = "contact_phone")
    protected String contactPhone;
    @XmlElement(name = "contact_fax")
    protected String contactFax;
    @XmlElement(name = "contact_email", required = true)
    protected String contactEmail;
    @XmlElement(name = "file_item_nbr", required = true)
    @XmlSchemaType(name = "nonNegativeInteger")
    protected BigInteger fileItemNbr;
}

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "extend_header", propOrder = {
    "vendor",
    "app",
    "sequence",
    "date",
    "extendData"
})
public class ExtendHeader {

    @XmlElement(required = true)
    protected String vendor;
    protected String app;
    protected String sequence;
    @XmlSchemaType(name = "date")
    protected XMLGregorianCalendar date;
    @XmlElement(name = "extend_data", required = true)
    protected List<ExtendData> extendData;
    }

Может кто-нибудь помочь, как проверить, есть ли у экземпляра Client вложенное свойство address_1 присутствует или нет, и если оно присутствует, имеет ли вложенное свойство непустое значение или нет?