Support marshalling of Java 14 records

[alamar]

Right now, attempting do to so results in

UnsupportedOperationException: can't get field offset on a record class: private final xxx..dto.Pathway xxx.dto.ClientIdentifierDto.pathway

[StevenCurran]

+1 this would be very useful!

[peter-lawrey]

In the short term we should produce a meaningful error message until this is properly supported.

• we should explore how this can be supported.
• whether object reuse is possible or desirable to reduce object allocations.