Prepare for Jackson-Tools-3 Uplift. (JT3)

[granadacoder]

This PR is NOT the (a) Jackson-Tools-3 Uplift.

This PR is adding more unit-tests on java-classes that will (eventually in a future PR) be substantially effected by the JT3 uplift.

This will help ensure that the JT3 uplift (later) does not break existing functionality.

4 new unit-test-only classes. And new tests in an existing unit-test class.

The unit-tests themselves were largely written by github-copilot. (I don't remember the model).
But the prompt was "Add covering unit-tests and pay attention to future Jackson-Tools-3 upgrade edge cases".

[tadgh]

Formatting check succeeded!

[granadacoder]

Bread Crumb 1:

https://github.com/hapifhir/hapi-fhir/blob/master/hapi-fhir-base/src/main/java/ca/uhn/fhir/parser/json/jackson/JacksonWriter.java#L45L62

This will be different in the future JT3 change.

Jackson-Tool-3 has changed to "immutable" "builder" approach.

So many "setters" .. for configuration are gone. And have to be a part of the pre builder-"build" command.

[granadacoder]

Bread Crumb 2 :

https://github.com/hapifhir/hapi-fhir/blob/master/hapi-fhir-base/src/main/java/ca/uhn/fhir/parser/json/jackson/JacksonStructure.java#L409L424

Same situation. JT3 will not be "setters". It will be the builder pattern.

[granadacoder]

Bread Crumb 3 :

https://github.com/hapifhir/hapi-fhir/blob/master/hapi-fhir-base/src/main/java/ca/uhn/fhir/util/JsonUtil.java#L60L81

Same situation. No configuration-setters in JT3. Builder pattern will be used for immutability.

[granadacoder]

Breadcrumb #4

https://github.com/hapifhir/hapi-fhir/blob/master/hapi-fhir-storage/src/main/java/ca/uhn/fhir/jpa/patch/JsonPatchUtils.java#L33L34

Deprecation of
https://github.com/java-json-tools

java-json-tools/json-patch#165 (comment)

....

and replacement:

FasterXML/jackson-datatype-jsr353#13

[jamesagnew]

Cool!