Bug 120503 Cascading Parameter can not drop into layout
Details: Cascading Parameter can not drop into layout Step: 1.Open a report design and Create a Sample Data Source and data set by "select * from CLASSICMODELS.CUSTOMERS" 2.New a cascading parameter and create CUSTOMERSNUMBER and CUSTOMERSNAME in parameter named number and name. Press OK 3.Drop parameter name into layout. Actual results: The parameter in Cascading Parameter Group can not drop to layout
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/util/DEUtil.java
*/
	public static boolean isSameString( String str1, String str2 )
	{
		if ( str1 == null && str2 == null )
		{
			return true;
		}
		if ( str1 != null && str1.equals( str2 ) )
		{
			return true;
		}
		return false;
	}
	/**
	 * Create a row expression base on column name.
	 * 
	 * @param columnName
	 * @return
	 */
	public static String getColumnExpression( String columnName )
	{
		Assert.isNotNull( columnName );
		if ( StringUtil.isBlank( columnName ) )
		{
			return null;
		}
		return IReportElementConstants.DATA_COLUMN_PREFIX
				+ "[\"" + DEUtil.escape( columnName ) + "\"]";
	}
	/**