/** PUBLIC: Default constructor. */
  public VariableOneToOneMapping() {
    this.selectionQuery = new ReadObjectQuery();
    this.sourceToTargetQueryKeyNames = new HashMap(2);
    this.typeIndicatorTranslation = new HashMap(5);
    this.typeIndicatorNameTranslation = new HashMap(5);
    this.foreignKeyFields = NonSynchronizedVector.newInstance(1);

    // right now only ForeignKeyRelationships are supported
    this.isForeignKeyRelationship = false;
  }
 /** INTERNAL: Return all attributes specified for batch reading. */
 public Vector getBatchReadAttributeExpressions() {
   if (batchReadAttributeExpressions == null) {
     batchReadAttributeExpressions = NonSynchronizedVector.newInstance();
   }
   return batchReadAttributeExpressions;
 }