Bug 202236 When select NULL value for multi-value parameter, cause NPE.
Description: When select NULL value for multi-value parameter, cause NPE. Build number: 2.2.1 Steps to reproduce: 1, New a list parameter, check Allow multi-value, uncheck isRequired 2, Select parameter data type as Date 3, Add some items into list 4, Preview 5, Select Null Value item in list Expected result: Can accept Null value for multi-value parameter Actual result: Cause NPE.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/EngineTask.java
public String getParameterDisplayText( String name )
	{
		Object parameter = inputValues.get( name );
		if ( parameter != null )
		{
			assert parameter instanceof ParameterAttribute;
			return ( (ParameterAttribute) parameter ).getDisplayText( );
		}
		return null;
	}
	public void setParameterDisplayTexts( Map params )
	{
		Iterator iterator = params.entrySet( ).iterator( );
		while ( iterator.hasNext( ) )
		{
			Map.Entry entry = (Map.Entry) iterator.next( );
			String name = (String) entry.getKey( );
			String text = (String) entry.getValue( );
			setParameterDisplayText( name, text );
		}
	}
	public void setParameterDisplayText( String name, String displayText )
	{
		parameterChanged = true;
		Object parameter = inputValues.get( name );
		if ( parameter != null )
		{
			assert parameter instanceof ParameterAttribute;
			( (ParameterAttribute) parameter ).setDisplayText( displayText );
		}