new ReferenceTypeUtils code fails with IllegalArgumentException with type.getType() is null

[pjfanning]

New code in ReferenceTypeUtils causes exception when using swagger-core with Scala Options.

java.lang.IllegalArgumentException: argument "t" is null
	at com.fasterxml.jackson.databind.ObjectMapper._assertNotNull(ObjectMapper.java:4885)
	at com.fasterxml.jackson.databind.ObjectMapper.constructType(ObjectMapper.java:2211)
	at io.swagger.v3.core.util.ReferenceTypeUtils.unwrapReference(ReferenceTypeUtils.java:35)
	at io.swagger.v3.core.converter.ModelConverterContextImpl.resolve(ModelConverterContextImpl.java:79)
	at io.swagger.v3.core.converter.ModelConverterContextImpl.resolve(ModelConverterContextImpl.java:81)
	at io.swagger.v3.core.converter.ModelConverters.readAll(ModelConverters.java:89)
	at io.swagger.v3.core.converter.ModelConverters.readAll(ModelConverters.java:80)
	at com.github.swagger.akka.converter.ModelPropertyParserTest.$anonfun$new$11(ModelPropertyParserTest.scala:163)

[pjfanning]

@frantuma would it be possible to consider adding this null guard? The new ReferenceTypeUtils breaks swagger usage for some Scala use cases.

[frantuma]

Thanks for spotting it and for the fix!

[pjfanning]

@frantuma - it turns out this change just leads to a stackoverflow in https://github.com/swagger-api/swagger-core/blob/master/modules/swagger-core/src/main/java/io/swagger/v3/core/converter/ModelConverterContextImpl.java#L81

I'm trying out an alternative change where ReferenceTypeUtils returns null if type.getType is null.

edit: I have added #4299 which seems to work better