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
changeControlType( );
		}
		lastDataType = type;
		if ( type.equals( DesignChoiceConstants.PARAM_TYPE_STRING ) )
		{
			clearDefaultValueChooser( isRequired.getSelection( ) );
		}
		else if ( !type.equals( DesignChoiceConstants.PARAM_TYPE_BOOLEAN ) )
		{
			clearDefaultValueText( );
			clearDefaultValueChooserSelections( );
		}
		initFormatField( );
		if ( isStatic( ) )
		{
			makeUniqueAndValid( );
			refreshValueTable( );
		}
		else
		{
			refreshColumns( true );
		}
		updateMessageLine( );
	}
	private boolean buildControlTypeList( String type )
	{
		String[] choices;
		if ( isStatic( ) )
		{
			if ( DesignChoiceConstants.PARAM_TYPE_BOOLEAN.equals( type ) )