Golang encoding/json/v2: Indent does not preserve trailing whitespace

https://pkg.go.dev/encoding/json#Indent:

[...] trailing space characters at the end of src are preserved and copied to dst. For example, if src has no trailing spaces, neither will dst; if src ends in a trailing newline, so will dst.

When GOEXPERIMENT=jsonv2, encoding/json.Indent no longer preserves trailing whitespace, contrary to the documentation.