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/MemberRef.java
}
			return null;
		}
		Structure struct = (Structure) element.getProperty( module, propDefn );
		if ( struct == null )
			return null;
		if ( index[0] >= 0 )
		{
			
			
			assert member[0].isList( );
			ArrayList list = (ArrayList) struct.getProperty( module, member[0] );
			return getStructure( list, 0 );
		}
		if ( member[1] != null )
		{
			
			assert !member[0].isList( );
			return (Structure) struct.getProperty( module, member[0] );
		}
		
		
		return struct;
	}
	/**
	 * Returns the definition of the structure pointed to by the reference.
	 * <p>
	 * <strong>property </strong> <br>
	 * <strong>property </strong>.member <br>
	 *