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
if ( struct == null )
			return null;
		if ( propDefn.isList( ) )
		{
			
			
			
			
			
			
			switch ( refType )
			{
				case PROPERTY :
					return getList( module, element );
				case PROPERTY_LISTn :
				case PROPERTY_LISTn_MEMBER_LISTn :
					return struct;
				case PROPERTY_LISTn_MEMBER : 
					return struct.getProperty( module, member[0] );
				case PROPERTY_LISTn_MEMBER_MEMBER :
				case PROPERTY_LISTn_MEMBER_LISTn_MEMBER :
					return struct.getProperty( module, member[1] );
				default :
				{
					assert false;
					return null;
				}
			}
		}