Issue #123: support nullable collections

[hofiisek]

Solves https://github.com/Randgalt/record-builder/issues/123

There's a new allowNullableCollections option that does the following:

• if set to false (default value for BC), does nothing
• if set to true and interpretNotNulls = false, a list/set/map/collection record component will return null if value is not set
• if set to true and interpretNotNulls = true, a list/set/map/collection record component will return null only if it's determined to be nullable, i.e. isn't annotated by any of the not-null patterns

All branches mentioned above should be covered by the TestNullableCollectionsBuilder test

[Randgalt]

Thanks for this. I'll have a look very soon

[Randgalt]

Thanks for this PR - it looks very good.

I tried a class that only has @RecordBuilder.Options(allowNullableCollections = true) and it's a NOP regarding specialized collections. Should we emit a warning or error? Or, should allowNullableCollections = true always imply enabling useImmutableCollections?

[hofiisek]

Thanks for this PR - it looks very good.

I tried a class that only has @RecordBuilder.Options(allowNullableCollections = true) and it's a NOP regarding specialized collections. Should we emit a warning or error? Or, should allowNullableCollections = true always imply enabling useImmutableCollections?

I see, didn't think of that combination before.

Since NOP is the expected behavior in this case (components and builder getters just return whatever you set to them, without any shim calls etc.), I think we can emit a warning that it will have no effect. I'd rather not enableuseImmutableCollections automatically as it changes behavior and it could possibly break someone's project (even though I would think that the majority uses unmodifiable/immutable collections anyway).

[Randgalt]

Since NOP is the expected behavior in this case (components and builder getters just return whatever you set to them, without any shim calls etc.), I think we can emit a warning that it will have no effect. I'd rather not enableuseImmutableCollections automatically as it changes behavior and it could possibly break someone's project (even though I would think that the majority uses unmodifiable/immutable collections anyway).

A warning (or error) would be good. I'd prefer that to doing nothing.

[hofiisek]

Agree. Added in the last commit :)

[Randgalt]

Thank you for this