nhibernate, chame a função no Oracle que retorna sys refcursor

Para Oracle, aplicam-se as seguintes regras :

Uma função deve retornar um conjunto de resultados. O primeiro parâmetro de um procedimento deve ser um OUT que retorne um conjunto de resultados. Isso é feito usando um tipo SYS_REFCURSOR no Oracle 9 ou 10. No Oracle você precisa definir um tipo REF CURSOR, consulte a literatura Oracle.

create or replace
PACKAGE           "MYPACKAGE" AS

    TYPE ReferenceCursor IS REF CURSOR;

    PROCEDURE  usp_GetDual 
    (
    pCursor OUT ReferenceCursor,
    a IN CHAR,
    b IN CHAR
    );

END MYPACKAGE;

PROCEDURE usp_GetDual
    (
          pCursor OUT ReferenceCursor,
          a IN CHAR,
          b IN CHAR
    )

  IS

    err_code NUMBER;
    err_msg VARCHAR2(200);

  BEGIN

  OPEN pCursor FOR
    SELECT * FROM dual;

   EXCEPTION
    WHEN OTHERS THEN 
        err_code := SQLCODE;
        err_msg := substr(SQLERRM, 1, 200);

END usp_GetDual;

<?xml version="1.0" encoding="utf-8"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="MyAssembly">
    <sql-query name="GetDaul">
        { call MYPACKAGE.usp_GetDual ( :a, :b ) }
    </sql-query>
</hibernate-mapping>

var value = Session.GetNamedQuery("GetDaul")
    .SetParameter<string>("a", "AAA")
    .SetParameter<string>("b", "BBB")
    .UniqueResult();

<?xml version="1.0" encoding="utf-8"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="MyAssembly">
    <sql-query name="GetOrders">
         <return class="MyAssembly.Domain.MyOrder, MyAssembly" />
         { call MYPACKAGE.usp_GetOrders ( :pCompanyCode , :pOrderNumer ) }
    </sql-query>
</hibernate-mapping>

public class MyOrder
{
    public virtual string Number { get; set; }
    public virtual int Ver { get; private set; }
    public virtual string Company { get; set; }
    public virtual string Customer { get; set; }

    public override bool Equals(object obj)
    {
        if (obj == null)
            return false;
        Order order = obj as Order;
        if (order == null)
            return false;
        if (this.Number.Trim() == order.Number.Trim() &&
            this.Ver == order.Ver &&
            this.Company.Trim() == order.Company.Trim()
            )
            return true;
        else
            return false;
    }

    public override int GetHashCode()
    {
        int hash = 0;
        hash = hash +
            (null == this.Number ? 0 : this.Number.GetHashCode())
            +
            (this.Ver.GetHashCode())
            +
            (null == this.Company ? 0 : this.Company.GetHashCode());

        return (hash);
    }
}

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="MyAssembly" namespace="MyAssembly.Domain">
  <class name="MyOrder" table="OCSAORH" mutable="false">
    <composite-id>
      <key-property name="Number" column="OCHORDN" type="String" length="10"></key-property>
      <key-property name="Ver" column="OCHAMND" type="Int32"></key-property>
      <key-property name="Company" column="OCHCOSC" type="String" length="5"></key-property>
    </composite-id>
    <property name="Customer" column="OCHCLII" type="String"></property>
  </class>
</hibernate-mapping>

PROCEDURE usp_GetOrders 
          (
          pCursor OUT ReferenceCursor,
          pCompanyCode IN CHAR,
          pOrderNumer IN CHAR
      )

  IS

    err_code NUMBER;
    err_msg VARCHAR2(200);

  BEGIN

  OPEN pCursor FOR
       SELECT 
            OCSAORH.*
      FROM OCSAORH 
            WHERE OCSAORH.OCHAMND = 0
                AND OCSAORH.OCHCOSC = pCompanyCode
                AND OCSAORH.OCHORDN = pOrderNumer;              
    EXCEPTION
            WHEN OTHERS THEN 
          err_code := SQLCODE;
          err_msg := substr(SQLERRM, 1, 200);

END usp_GetOrders;

var listOfOrders = Session.GetNamedQuery("GetOrder")
    .SetParameter<string>("pCompanyCode", "ABC")
        .SetParameter<string>("pOrderNumer", "XYZ")
        .List<Domain.MyOrder>();