[Kotlin-Spring] Fix properties default value

[cbornet]

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[wing328]

LGTM

[sticreations]

Hi, Sadly this introduced a new Bug when generating default Enum Values.

The name of the generated Enum is for example "TemperatureZone", the generated Code for the default value is
**` @field:JsonProperty("temperature_zone") var temperatureZone: OutboundZone.TemperatureZone? = TemperatureZoneEnum.NONE
**

The default value seems to get the classname wrong.

[sigand]

It seems to also so something to default values for strings. Generated code does not compile
@field:JsonProperty("exampleProperty") val exampleProperty: kotlin.String? = "example",

[sigand]

Having played around in the code, neither bug above is due to this PR