Bug 190727 [regression]Default value issue when switch report parameter from textbox to listbox.[0705]
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
String errorMessage = validateName( );
		if ( errorMessage == null )
		{
			
			if ( !isStatic( )
					&& columnChooser != null
					&& columnChooser.getItemCount( ) == 0 )
			{
				errorMessage = ERROR_MSG_NO_AVAILABLE_COLUMN;
			}
			
			if ( defaultValue == null
					&& ( PARAM_CONTROL_COMBO.equals( getSelectedControlType( ) ) || DesignChoiceConstants.PARAM_CONTROL_RADIO_BUTTON.equals( getSelectedControlType( ) ) ) )
			{
				
				
				
				
				
				
				
				
				
				
				
				
				errorMessage = canBeNull( ) ? null : ERROR_MSG_NO_DEFAULT_VALUE;
			}
		}
		if ( errorMessage != null )