fix: support null handling in nested structures

[Shahroz16]

closes: MBL-955

Changes

• Added sanitizeNullsForJson() extension to recursively replace all null values with JsonNull in CustomAttributes for Map and List before forwarding to analytics
• Added unit tests to validate the behavior of new extension
• Added tests on CustomerIO.instance to validate end-to-end behavior
• Updated Datapipeline method to cater Map<String,Any?> so they can cater cases of both, CustomeAttribute and mapof type <string, any?>

Sample Code

Crash on main before this fix:

CustomerIO.instance().track(
    "Add to Cart",
    mapOf(
        "item" to mapOf(
            "id" to "100",
            "name" to "Mobile",
            "discount" to null,
        ),
    )
)

[github-actions]

Sample app builds 📱

Below you will find the list of the latest versions of the sample apps. It's recommended to always download the latest builds of the sample apps to accurately test the pull request.

---

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.45%. Comparing base (26b4621) to head (5adacc4).
Report is 5 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #508      +/-   ##
============================================
+ Coverage     52.02%   52.45%   +0.43%     
- Complexity      318      319       +1     
============================================
  Files           105      104       -1     
  Lines          2862     2888      +26     
  Branches        381      384       +3     
============================================
+ Hits           1489     1515      +26     
  Misses         1259     1259              
  Partials        114      114              

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[github-actions]

Build available to test
Version: mbl-955-fix-nested-null-parsing-SNAPSHOT
Repository: https://s01.oss.sonatype.org/content/repositories/snapshots/

[github-actions]

• java_layout: mbl-955-fix-nested-null-parsing (1744105183)

[github-actions]

• kotlin_compose: mbl-955-fix-nested-null-parsing (1744105171)

[mrehan27]

Looks good 👍🏻

We can roll it out after testing the changes on wrapper SDKs.

[mahmoud-elmorabea]

Approach looks solid! 💯

Just wanted to double check on two main concerns:

• I think we might have missed at least one place using CustomAttributes, maybe it's worth doing a search for it to make sure we covered all. I only found one though
• I cross tested with iOS quickly and it seems like iOS omits the value all together rather than sending it null, but it's not consistent, have we cross checked behavior with iOS?

[Shahroz16]

• I cross tested with iOS quickly and it seems like iOS omits the value all together rather than sending it null, but it's not consistent, have we cross checked behavior with iOS?

Thats a good callout, I agree with consistency but I also don't want to introduce a breaking change in terms of behavior. For example, currently null in the parent are treated as JsonNull and not skipped.

If we add logic of skipping nulls, then even that current behavior is going to be changed and if anyone has any segments/events driven based on that current behavior, it could break for them

[github-actions]

• java_layout: mbl-955-fix-nested-null-parsing (1744293869)

[github-actions]

• kotlin_compose: mbl-955-fix-nested-null-parsing (1744293885)