Bug 182673 No default value error message prompts incorrectly
Steps to reproduce: 1. New a report parameter; 2. Choose control type as Combo; 3. Choose parameter as dynamic type; Expected result: As the isRequired is false by default, parameter's default value can be null value. There should be no error message about no default value prompt. Actual result; Error messages prompts
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/CascadingParametersDialog.java
}
				catch ( NameException e )
				{
					ExceptionHandler.handle( e );
				}
			}
			if ( COLUMN_DATA_SET.equals( property ) )
			{
				try
				{
					if ( isSingle( ) )
					{
						inputParameterGroup.setDataSet( getDataSet( (String) value ) );
					}
					else
					{
						( (ScalarParameterHandle) actualElement ).setDataSetName( (String) value );
					}
				}
				catch ( SemanticException e )
				{
					ExceptionHandler.handle( e );
				}
			}
			else if ( COLUMN_VALUE.equals( property ) )
			{
				try
				{
					( (ScalarParameterHandle) actualElement ).setValueExpr( DEUtil.getColumnExpression( (String) value ) );
				}