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/ParameterDialog.java
}
			}
			refreshValueTable( );
		}
		else
		{
			refreshDataSets( );
			if ( inputParameter.getDataSetName( ) != null )
			{
				dataSetChooser.setText( inputParameter.getDataSetName( ) );
			}
			refreshColumns( false );
			String columnName = getColumnName( inputParameter.getValueExpr( ) );
			if ( columnName != null )
			{
				columnChooser.setText( columnName );
			}
			columnName = getColumnName( inputParameter.getLabelExpr( ) );
			if ( columnName != null )
			{
				displayTextChooser.setText( columnName );
			}
			if ( getSelectedDataType( ).equals( DesignChoiceConstants.PARAM_TYPE_STRING ) )
			{
				if ( defaultValue == null )
				{
					defaultValueChooser.select( 1 );
				}
				else if ( defaultValue.equals( "" ) )
				{