Fixed the filtering of duplicate columns

[grzesiek2010]

Why is this the best possible solution? Were any other approaches considered?

It turns out that properties might come in different order causing the problem that my tests didn't take into account, see:
https://github.com/getodk/collect/pull/6543/files#diff-c1535b2e1da246141cdc344e2d23e0ec8897df03e4055fd171a82a64cd0907a4R762

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

Just continue testing that yu started in #6538.

Do we need any specific form for testing your changes? If so, please attach one.

No.

Does this change require updates to documentation? If so, please file an issue here and include the link below.

No.

Before submitting this PR, please make sure you have:

• added or modified tests for any new or changed behavior
• run ./gradlew connectedAndroidTest (or ./gradlew testLab) and confirmed all checks still pass
• added a comment above any new strings describing it for translators
• added any new strings with date formatting to DateFormatsTest
• verified that any code or assets from external sources are properly credited in comments and/or in the about file.
• verified that any new UI elements use theme colors. UI Components Style guidelines

[seadowg]

I think we can break this into two test now as it feels like we're accounting for two distinct (but very related cases):

1. When an entity is created with duplicate case-insensitive properties
2. When an entity is created with a new property that's a case-insensitive duplicate of an existing one.

So basically we can have one test that just checks saving something like:

val entity = Entity.New(
    "1",
    "One",
    properties = listOf(Pair("prop", "value"), Pair("Prop", "value"))
)

And another that checks saving a new entity to an existing list with a case-insensitive duplicate property like:

val repository = buildSubject()
val entity = Entity.New(
    "1",
    "One",
    properties = listOf(Pair("prop", "value"))
)

repository.save("things", entity)
var savedEntities = repository.getEntities("things")
assertThat(savedEntities[0].properties.size, equalTo(1))
assertThat(savedEntities[0].properties[0].first, equalTo("prop"))

repository.save("things", entity.copy(properties = listOf(Pair("Prop", "value"))))
savedEntities = repository.getEntities("things")
assertThat(savedEntities[0].properties.size, equalTo(1))
assertThat(savedEntities[0].properties[0].first, equalTo("prop"))

I'm pretty sure that'll drive out both the distintBy and the filterNot processing we have to do and give us different fails if one or the other is missing. Mainly though, I think it'll make it easier to understand the intended behaviour from the tests.

[WKobus]

Tested with Success

Verified on device with Android 15

Verified cases:

• Duplicate properties in entity registration form
• Duplicate properties in entity update form

[dbemke]

Tested with Success

Verified on device with Android 10