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
{
				SelectionChoiceHandle choiceHandle = (SelectionChoiceHandle) iter.next( );
				choiceList.add( choiceHandle.getStructure( ) );
			}
		}
		else
		{
			dynamicRadio.setSelection( true );
		}
		defaultValue = inputParameter.getDefaultValue( );
		if ( DesignChoiceConstants.PARAM_TYPE_DATETIME.equals( getSelectedDataType( ) ) )
		{
			try
			{
				defaultValue = convertToStandardFormat( DataTypeUtil.toDate( defaultValue ) );
			}
			catch ( BirtException e )
			{
				ExceptionHandler.handle( e );
				return false;
			}
		}
		if ( inputParameter.getPropertyHandle( ScalarParameterHandle.LIST_LIMIT_PROP )
				.isSet( ) )
		{
			listLimit.setText( String.valueOf( inputParameter.getListlimit( ) ) );
		}
		isHidden.setSelection( inputParameter.isHidden( ) );