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
{
				choices = new String[3];
			}
			else
			{
				choices = new String[4];
			}
		}
		else
		{
			choices = new String[2];
		}
		if ( controlTypeChooser.getItemCount( ) != choices.length )
		{
			String originalSelection = controlTypeChooser.getText( );
			if ( isStatic( ) )
			{
				if ( DesignChoiceConstants.PARAM_TYPE_BOOLEAN.equals( type ) )
				{
					choices[0] = CONTROL_TYPE_CHOICE_SET.findChoice( DesignChoiceConstants.PARAM_CONTROL_CHECK_BOX )
							.getDisplayName( );
					choices[1] = DISPLAY_NAME_CONTROL_COMBO;
				}
				else
				{
					choices[0] = CONTROL_TYPE_CHOICE_SET.findChoice( DesignChoiceConstants.PARAM_CONTROL_TEXT_BOX )
							.getDisplayName( );
					
					choices[1] = DISPLAY_NAME_CONTROL_COMBO;
					choices[2] = DISPLAY_NAME_CONTROL_LIST;