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
switch ( defaultValueChooser.getSelectionIndex( ) )
				{
					case 0 :
						defaultValue = null;
						break;
					case 1 :
						defaultValue = Boolean.toString( true );
						break;
					case 2 :
						defaultValue = Boolean.toString( false );
						break;
				}
			}
		} );
	}
	private void switchToList( )
	{
		createLabel( valueArea, LABEL_VALUES );
		Composite tableAreaComposite = new Composite( valueArea, SWT.NONE );
		tableAreaComposite.setLayout( UIUtil.createGridLayoutWithoutMargin( ) );
		tableAreaComposite.setLayoutData( new GridData( GridData.FILL_BOTH ) );
		TableArea tableArea = new TableArea( tableAreaComposite, SWT.SINGLE
				| SWT.FULL_SELECTION
				| SWT.BORDER, tableAreaModifier );
		tableArea.setLayoutData( new GridData( GridData.FILL_BOTH ) );
		Table table = tableArea.getTable( );
		table.setLinesVisible( true );
		table.setHeaderVisible( true );
		String[] columns;
		int[] columnWidth;