Don't let Jackson drop the "is" prefix when serializing a Kotlin class to JSON

BooleanNamingStrategy.kt

// adapted from https://stackoverflow.com/a/51419993/516910

package to.pubsub.util

import com.fasterxml.jackson.databind.PropertyNamingStrategy
import com.fasterxml.jackson.databind.cfg.MapperConfig
import com.fasterxml.jackson.databind.introspect.AnnotatedField
import com.fasterxml.jackson.databind.introspect.AnnotatedMethod

class BooleanNamingStrategy : PropertyNamingStrategy() {

    override fun nameForGetterMethod(config: MapperConfig<*>, method: AnnotatedMethod, defaultName: String): String {
        if (method.hasReturnType() && (method.rawReturnType.name == "boolean" || false) && method.name.startsWith("is")) {
            return method.name
        }
        else {
            return super.nameForGetterMethod(config, method, defaultName)
        }
    }

    override fun nameForField(config: MapperConfig<*>, field: AnnotatedField, defaultName: String): String {
        if (field.rawType.name == "boolean" && field.name.startsWith("is")) {
            return field.name
        }
        else {
            return super.nameForField(config, field, defaultName)
        }
    }

}

JsonMapper.kt

// Wherever you setup your main object mapper, register this naming strategy
val myMainObjectMapper = ObjectMapper().apply {
    setPropertyNamingStrategy(BooleanNamingStrategy())
    // more setting
    // etc..
}