Enforce AASd-108

[arnoweiss]

As per spec, a SubmodelElementList can only hold a single type of SubmodelElement [1]. AAS4J does currently not technically enforce this. For example, in one of the test-examples, this constraint is violated as a SMEL contains a Property, a MultiLanguageProperty and a Range.

This could for example be done by changing the class signature:

public interface SubmodelElementList<E extends SubmodelElement> extends SubmodelElement{

/*
lots of other stuff
*/

@IRI("https://admin-shell.io/aas/3/0/SubmodelElementList/value")
List<E> getValue();

Con:

• This would not be generatable.
• There's no concensus in AAS4J on how to deal with constraints generally.

[1] https://aas-core-works.github.io/aas-core-meta/v3/SubmodelElementList.html#constraint-AASd-108
[2]

aas4j/dataformat-core/src/test/java/org/eclipse/digitaltwin/aas4j/v3/dataformat/core/AASFull.java

Line 652 in 1c4a6b8

.submodelElements(new DefaultSubmodelElementList.Builder()