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
else
				{
					changeDefaultValue( choice.getValue( ) );
				}
				refreshValueTable( );
				changeDefault.getParent( ).layout( );
			}
		} );
		createPromptLine( tableAreaComposite );
		updateTableButtons( );
	}
	private void switchToText( )
	{
		createDefaultEditor( );
		createLabel( valueArea, null );
		createPromptLine( valueArea );
	}
	private void switchToStatic( )
	{
		changeControlType( );
		listLimit.setEditable( false );
	}
	private void switchToDynamic( )
	{
		Composite composite = new Composite( valueArea, SWT.NONE );
		GridData gd = new GridData( GridData.FILL_HORIZONTAL );
		gd.horizontalSpan = 2;
		composite.setLayoutData( gd );
		composite.setLayout( UIUtil.createGridLayoutWithoutMargin( 3, false ) );
		createLabel( composite, LABEL_SELECT_DATA_SET );