Discussion: How to handle extensions

This is a spin-off issue from #302 which discusses 2 issues focused on how to support Extension subclasses.

According to the SPDX AIPackage specification an optional property field is extension. This field is of type Extension.

Extension is an abstract class so it can't be instantiated.

Referencing an Extension in the JSON-LD without parameters passes the Java coded validation but fails the JSON schema validation (see related https://github.com/spdx/spdx-3-model/issues/1017):

"extension" : [
			{
				"type" : "extension_Extension"
			}
		]

Adding a parameter:

"extension" : [
			{
				"type" : "extension_Extension",
				"randomProperty" : "test"
			}
		]

causes the Java parser to fail with Analysis exception processing SPDX file: No property descriptor for field randomProperty.

Adding any additional type will also cause the Java code to fail.

Is there an approach where we can allow Extensions in the Java library?

Inizia con la specifica SPDX AIPackage e gli esempi JSON-LD presenti in questa issue, quindi segui i percorsi del parser Java e della validazione dello schema JSON che elaborano il campo di estensione. Confronta il modo in cui viene rappresentata una Extension astratta e identifica i vincoli del progetto che devono essere risolti. Il lavoro è completato quando sarà stato concordato un approccio per consentire le Extensions senza gli attuali errori di validazione o di property-descriptor.