package com.doomspork.helloworld

import io.dropwizard.Configuration
import org.hibernate.validator.constraints.NotEmpty
import com.fasterxml.jackson.annotation.JsonProperty
import com.fasterxml.jackson.annotation.JsonCreator

data class HelloWorldConfiguration [JsonCreator] (JsonProperty("template") NotEmpty var template: String,
                                                  JsonProperty("defaultName") NotEmpty var defaultName: String) : Configuration()


package com.doomspork.helloworld

import com.fasterxml.jackson.annotation.JsonProperty
import io.dropwizard.Configuration

public class HelloWorldConfiguration() : Configuration() {
    @JsonProperty("template")
    public var template: String=""

    @JsonProperty("defaultName")
    public var defaultName: String="Stranger"
}

Change data class to normal class as data class inheritance has been removed.
Change data class to normal class as data class inheritance has been removed.

doomspork/kotlin-dropwizard