[backport into 4.x] correct property values from enums are sometimes flagged as error

[martinlippert]

Backport issue for #1605 for the 4.32.0 release:

management.endpoint.health.show-details=when_authorized

is flagged as an error, even though the Spring Boot internally converts when_authorized correctly to Show.WHEN_AUTHORIZED.

It looks like the validation logic around enum values for properties is currently:

• lower-case name of the enum with - instead of _ (when-authorized does not show an error)
• upper-case exact name of the enum (WHEN_AUTHORIZED does not show an error)

But the conversion logic in Spring Boot is a little different. It is located in LenientObjectToEnumConverterFactory. It basically is:

• does the value match the exact enum value (in this case WHEN_AUTHORIZED)
• if not, then strip all non-digit and non-letter characters, convert to lowercase, and find the enum value that way.

That results in:

• when_authorized is mapped to WHEN_AUTHORIZED
• when-authorized is mapped to WHEN_AUTHORIZED
• WHEN-AUTHORIZED is mapped to WHEN_AUTHORIZED

This should be reflected in the validation logic for the property editors (.properties + .yml).

[BoykoAlex]

Fixed in 4.x via e7e6823