Bug 213973 [2.2.2]ClassCastException throws out when preview a table share crosstab
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/dte/ReportQueryBuilder.java
IBaseQueryDefinition query )
		{
			String name = design.getName( );
			List groups = query.getGroups( );
			if ( groups != null && groups.size( ) > 0 )
			{
				for ( int i = 0; i < groups.size( ); i++ )
				{
					IGroupDefinition group = (IGroupDefinition) groups.get( i );
					if ( group.getName( ).equals( name ) )
					{
						return group;
					}
				}
			}
			EngineException ex = new EngineException( "Invalid group {0}", name );
			logger.log( Level.WARNING, ex.getMessage( ), ex );
			context.addException( design.getHandle( ), ex );
			return null;
		}
		/**
		 * processes a table/list group
		 */
		protected IGroupDefinition handleGroup( GroupDesign group,
				GroupHandle handle, IBaseQueryDefinition query )
		{
			GroupDefinition groupDefn = new GroupDefinition( group.getName( ) );
			groupDefn.setKeyExpression( handle.getKeyExpr( ) );
			String interval = handle.getInterval( );
			if ( interval != null )