Fixes a bug where the JSON function with JSONFormat.FlattenValueTables argument was not working correctly when the input value is an IUntypedObject.

[Robulane]

Summary

Fixes a bug where the JSON function with JSONFormat.FlattenValueTables argument was not working correctly when the input value is an IUntypedObject.

Problem

When JSON function received an IUntypedObject representing an array of single-column "Value" objects (like [{Value:1},{Value:2},{Value:3}]), the JSONFormat.FlattenValueTables argument was being ignored. The function would output the full object structure
[{"Value":1},{"Value":2},{"Value":3}] instead of the flattened version [1,2,3].

Root Cause

In JsonFunctionImpl.cs, the Visit(IUntypedObject) method processed arrays without checking the _flattenValueTables flag, unlike the Visit(TableValue) method which correctly handled this flag.

Changes Made

1. JsonFunctionImpl.cs: Modified IUntypedObject array handling to check for single-column "Value" objects and flatten them when the flag is set
2. JsonSerializeUOTests.cs: Added comprehensive unit tests covering:
   • Flattening single-column Value arrays
   • Preserving structure without the flag
   • Not flattening multi-column objects
   • Handling null values correctly

Test plan

• Added new test: JsonSerializeUOWithFlattenValueTablesTest
• Existing JSON.txt test cases continue to pass
• Build succeeds with no warnings or errors

[anderson-joyle]