Try to remove non-nullable converter if duplicate found for nullable targetType

[julek-kal]

Connection with issue(s)

Close #1339

Solution description

When targetType is nullable and the class is annotated with both converters for nullable and non-nullable type, _compatibleMatch returns two of them. So I've added a check if targetType is nullable and matchingAnnotations length is equal to 2, if so I proceed to try to find a non-null converter and remove it from the list of matchedConverters.

To Do

• [x] Check the original issue to confirm it is fully satisfied
• [x] Add solution description to help guide reviewers
• [x] Add unit test to verify new or fixed behaviour
• [ ] If apply, add documentation to code properties and package readme

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