Bug 153405 Null parameter value is inconsistent between designer and preview
Description: Null parameter value is inconsistent between designer and preview Steps to reproduce: 1. New a report parameter, list-box, tick AllowNull. 2. Click New button, click OK without input anything. 3. Drag the parameter to Layout and preview Actual result: After step2, display text is "Null" and value is empty. However, when preview, the display text is "Null Value". Expected result: Display text and value should be consistent between Edit Parameter Dialog in Layout and Parameter dialog during preview.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
if ( DesignChoiceConstants.PARAM_TYPE_STRING.equals( type ) )
		{
			choiceSet = DEUtil.getMetaDataDictionary( )
					.getChoiceSet( DesignChoiceConstants.CHOICE_STRING_FORMAT_TYPE );
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_DATETIME.equals( type ) )
		{
			choiceSet = DEUtil.getMetaDataDictionary( )
					.getChoiceSet( DesignChoiceConstants.CHOICE_DATETIME_FORMAT_TYPE );
		}
		else if ( DesignChoiceConstants.PARAM_TYPE_DECIMAL.equals( type )
				|| DesignChoiceConstants.PARAM_TYPE_FLOAT.equals( type )
				|| DesignChoiceConstants.PARAM_TYPE_INTEGER.equals( type ) )
		{
			choiceSet = DEUtil.getMetaDataDictionary( )
					.getChoiceSet( DesignChoiceConstants.CHOICE_NUMBER_FORMAT_TYPE );
		}
		return choiceSet;
	}
	private void updateFormatField( )
	{
		String displayFormat;
		String previewString;
		String type = getSelectedDataType( );
		IChoiceSet choiceSet = getFormatChoiceSet( type );
		if ( choiceSet == null )
		{
			displayFormat = DEUtil.getMetaDataDictionary( )
					.getChoiceSet( DesignChoiceConstants.CHOICE_STRING_FORMAT_TYPE )
					.findChoice( DesignChoiceConstants.STRING_FORMAT_TYPE_UNFORMATTED )