Idiomatic way of branching json parsing in kotlin

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2

You probably want a combination here (I’m not that familiar with ObjectMapper, but canDeserialize could avoid the try/catch. The rest is as follows:

fun <T> ObjectMapper.treeToValueOrNull(n: TreeNode, valueType: Class<T>):T? = try {
    treeToValue(n, valueType)
} catch (e: JsonProcessingException) {
    null
}

val mapper = ObjectMapper()
return mapper.treeToValueOrNull(jsonNodeObj, ClassA::class.java) ?:
       mapper.treeToValueOrNull(jsonNodeObj, ClassB::class.java) ?:
       mapper.treeToValueOrNull(jsonNodeObj, ClassC::class.java) ?:
       throw IllegalArgumentException("The node doesn't map to A, B or C")

Btw. you may make it prettier by using a refied type parameter on an inline version

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