Symfony version(s) affected

6.3.6

Description

#52021 introduced an issue when form collection contains zero indexed item.

When submitting form with zero indexed collection item its values are reindexed.

There was an attempt to fix this in b769b77 but it was not enough for this case. As the original issue is closed. There is new one.

How to reproduce

See reproducer with test case and proposed change:
https://github.com/symfony/symfony/compare/6.4...jan-pintr:symfony-form-zero-indexed-collection-reporoducer:form-zero-indexed-col-reproducer?expand=1

Possible Solution

Reproducer contains proposed change to FormUtil::mergeParamsAndFiles() function.

Additional Context

No response