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class NaiveFileMetadataManagerTest
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[2021/12/18, minor textual edit]  testGetDataFileWrongFile()
This is just a test to show how we handle the case of exceptions being fired during execution of tests.
It ended up there when my implementation fired a NullPointerException when I passed a null File as a parameter to 
the constructor that I used, and my implementation issued a NullPointerException.
In case your implementation covers that, and no Exception is fired, the test will fail.
=> For all practical purposes, you can comment-out the @Test annotation and then it is not executed.

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class StructuredFileManagerTest
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[2021/12/11]   all the invocations of fileManager.getFileColumnNames() in the various @Test
The interface StructuredFileManagerInterface prescribes a null return value for the method
   public String[] getFileColumnNames(String pAlias)
in case of a non-existent file.
The test, on the other hand, assumes that the method returns a zero-sized aray of strings /* return new String[0]; */
So, these two are imcompatible.
=> you can fix this in any way you prefer:
(a) in your class that materializes StructuredFileManagerInterface, make the method getFileColumnNames() return a null value for non-registered files, and modify the test correctly
or
(b) modify the prescription of the method and return a zero-sized array of strings instead of a null

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class NaiveApplicationController
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[2021/12/11] class NaiveApplicationController should be used a demo class to help you build your own AppController.
Instead of changing NaiveApplicationController, better build one of your own.