[4.0] Small refactor of typehint check in CMSPlugin

[SharkyKZ]

Summary of Changes

Follow up to #30581.
Renames poorly named checkTypeHint() method and makes it private.
Changes it to accept ReflectionParameter instead of ReflectionType to maintain the whole parameter logic inside.

Testing Instructions

Test that Joomla and plugins still work.

Documentation Changes Required

No, unless the method was documented somewhere.

[adj9]

I have not tested this item.

With PR enabled the plugins are active and do not remain. I logged out and logged in from the administrative panel and there are no anomalies.

With these tests, can I confirm the PR?

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[SharkyKZ]

Yes, as long as it's working as before it's fine.

[ceford]

I have tested this item ✅ successfully on 1f6b0b4

I applied th patch and checked Joomla still works - it does. I put a die; in the new function to check it is being called - it is. All good.

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/30907.}

[particthistle]

I have tested this item ✅ successfully on 1f6b0b4

Tested, Joomla continued working.

Hard to find a plugin that the test would either fail for before the test. Harder to find one that would fail for Joomla 4 after the test without writing one. Plugins where parameters are not typehinted I would imagine are unusual?

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/30907.}

[alikon]

RTC

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/30907.}

[laoneo]

Thanks!