Bug 181121 Model should provide utility method for cube to get correspond dimension key.
In model cube handle, the relation of cube data set and dimension data sets are managed by a series of dimension condition handles.We need model to add utility method so that we can easily get corresponding dimension data set column names according to given cube dimension keys.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Structure.java
{
			ElementRefValue refValue = (ElementRefValue) value;
			return ReferenceValueUtil.needTheNamespacePrefix( refValue, module );
		}
		return value;
	}
	/**
	 * Gets the locale value of a property.
	 * 
	 * @param module
	 *            the module
	 * 
	 * @param propDefn
	 *            definition of the property to get
	 * @return value of the item as an object, or null if the item is not set
	 *         locally or is not found.
	 */
	public Object getLocalProperty( Module module, PropertyDefn propDefn )
	{
		Object value = resolveElementReference( module,
				(StructPropertyDefn) propDefn );
		if ( value != null )
			return value;
		if ( propDefn.isIntrinsic( ) )
			return getIntrinsicProperty( propDefn.getName( ) );
		return null;
	}
	/**
	 * Resolves a property element reference. The reference is the value of a
	 * property of type property element reference.