TerminologyCode type serializes wrong to JSON when using standardsCompliant config

[MattijsK]

There seems to be an override to the type in the json object for TerminologyCode which makes the type field always be @type. This is incorrect when using the standards compliant jackson config as it should become "_type".

The problem seems to be the Annotation in TerminologyCode.java:
@JsonTypeInfo(use=JsonTypeInfo.Id.NAME, defaultImpl=TerminologyCode.class)

[J3173]

We should check that the old data (with @type) and the new data (with _type) can be deserialized with the old and new version. We could check this with a test (maybe something exists?), but if that's unpractical, manual testing is also fine.