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/parser/StructureState.java
* The definition of the list property which this structure is in.
	 */
	PropertyDefn propDefn = null;
	/**
	 * The dictionary for structure class and name mapping.
	 */
	private static Map structDict = null;
	/**
	 * The structure which holds this property as a member.
	 */
	protected IStructure parentStruct = null;
	/**
	 * Constructs the state of the structure which is one property.
	 * 
	 * @param theHandler
	 *            the design parser handler
	 * @param element
	 *            the element holding this structure to parse
	 */
	StructureState( ModuleParserHandler theHandler, DesignElement element )
	{
		super( theHandler, element );
	}
	/**
	 * Constructs the state of the structure which is in one structure list.
	 * 
	 * @param theHandler
	 *            the design parser handler
	 * @param element
	 *            the element holding this structure