Map config item with the map values gets the wrong keys

Describe the bug

With this config item:

/**
     * Configuration of the individual parsers.
     * For example:
     *
     * <pre>
     * quarkus.tika.parsers = pdf
     * quarkus.tika.parser-options.pdf.sort-by-position = true
     */
    @ConfigItem
    public Map<String, Map<String, String>> parserOptions;

the first segment following the name of the config item (pdf) is lost.

Before the major config update I was seeing the map initialized as follows, given the above config fragment:

pdf (key): sort-by-position = true (single entry map value, sort-by-position - key, true - value)

Now I’m seeing:

sort-by-position (key): sort-by-position = true (single entry map value, sort-by-position - key, true - value)

so the pdf bit is lost.

(I think a similar issue may affect this configuration)

CC @dmlloyd

[dmlloyd]

I have a fix, but #5989 has to be merged first due to conflicts.

[sberyozkin]

@dmlloyd thanks, I will follow up with the #4360 rebase after the fix is in