<class name="ParsysUser" discriminator-value="U">
    <id name="code" type="long" column="code" unsaved-value="null">
      <generator class="native" />
    </id>
    <discriminator column="type" type="character" />   
    <property name="name" type="string" />
    <property name="password" type="string" />

    <subclass name="RemoteSystem"
       discriminator-value="R" dynamic-update="true"
       dynamic-insert="true">
    </subclass>
    <subclass name="CentralOperator"
       discriminator-value="C" dynamic-update="true"
       dynamic-insert="true">
       <many-to-one name="personalInfo" class="Person" column="personalInfo"/>
    </subclass>
    <subclass name="AgencyOperator"
       discriminator-value="A" dynamic-update="true"
       dynamic-insert="true">
       <many-to-one name="personalInfo" class="Person" column="personalInfo"/>
       <many-to-one name="branchOffice" class="BranchOffice" column="branchOffice"/>
    </subclass>
    <subclass name="es.parsec.parsys.user.Supplier"
       discriminator-value="S" dynamic-update="true"
       dynamic-insert="true">
       <many-to-one name="personalInfo" class="Person" column="personalInfo"/>
    </subclass>
    <subclass name="es.parsec.parsys.user.Visitor"
       discriminator-value="V" dynamic-update="true"
       dynamic-insert="true">
    </subclass>
   
</class>


<class name="Person">
    <id name="code" type="long" column="code" unsaved-value="null">
      <generator class="native" />
    </id>
    <property name="firstName" type="string" />
    <property name="middleName" type="string" />
    <property name="lastName" type="string" />
</class>

public class ParsysUser implements Principal
{
   public static String REMOTE_SYSTEM = "R";
   public static String CENTRAL_OPERATOR = "C";
   public static String AGENCY_OPERATOR = "A";
   public static String SUPPLIER = "S";
   public static String VISITOR = "V";
   
   private Long code;
   private String name;
   private String password;
   private String type;

// follows setters and getters...
}

public class AgencyOperator extends ParsysUser
{
   private Person personalInfo;
   private BranchOffice branchOffice;
// follows setters and getters...
}


public class Person {
   
    private Long code;
   private String firstName;
   private String middleName;
   private String lastName;

// follows getters and setters
}

net.sf.hibernate.QueryException: could not resolve property type: personalInfo [from ParsysUser as age where age.class = AgencyOperator  order by age.personalInfo.firstName asc]