Bug 153391 Some Options in Edit Parameter dialog haven't been saved.
Description: Some Options in Edit Parameter dialog haven't been saved. Steps to reproduce: 1. new a parameter, boolean type, tick AllowNUll and sort alphabetically... 2. Close the dialog and reopen it. 3. new a parameter, string, combo-box, tick AllowNull. 4. Close the dialog and reopen it. Expected result: Ticked options' status are saved Actual result: After reopen parameter dialog, options are unticked.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/ParameterDialog.java
* 
	 * @param value
	 *            the value to check
	 * @return Returns the error message if the input value is invalid,or null
	 *         if it is valid
	 */
	private String isValidValue( String value )
	{
		if ( canBeNull( ) )
		{
			if ( value == null || value.length( ) == 0 )
			{
				return null;
			}
		}
		else
		{
			if ( value == null || value.length( ) == 0 )
			{
				return ERROR_MSG_CANNOT_BE_NULL;
			}
		}
		if ( canBeBlank( ) )
		{
			if ( StringUtil.isBlank( value ) )
			{
				return null;
			}
		}
		else