for the moment I've only tried one-to-one but I did not find in XML the properties de map all columns of my composite keys.
Here is the actual mapping below.  "CROMOUVEMENT" is a detail table for "CROFINANCEREGLEMENT"      
Code:
<class name="com...Report.FinancialPaymentReport" table="CROFINANCEREGLEMENT">
      <composite-id>
         <key-property name="pk" column="NUMMOUVEMENT"/>
         <key-property name="operationId" column="NUMOPERATION" />
         <key-property name="company" column="SOC"/>
         <key-property name="source" column="SOURCE"/>
      </composite-id>
      <property name="mode" column="CODEMODEREGLEMENT" />
      ....
   </class>
        <class name="com...Report.FinancialMovementReport" table="CROMOUVEMENT">
      <composite-id>
         <key-property name="pk" column="NUMMOUVEMENT"/>
         <key-property name="operationId" column="NUMOPERATION" />
         <key-property name="source" column="SOURCE"/>
      </composite-id>
      <property name="nature" column="NATURE" />
      <property name="transactionId" column="TRANSACTIONID" />
      <property name="bordereauId" column="BORDEREAUID" />
      <property name="declarationId" column="DECLARATIONID" />
      ....
   </class>