data class H(
  val k: K?,
  ...,
  val z: Z?
)

... ... ... ...

data class K(
  var h: String?,
  var k: Boolean?,
  ...,
  var z: Int?
)

... ... ... ...

data class A(
  val h: H?,
  ...,
  val z: Z?
)

val breadCrumb :  MutableList<String> = mutableListOf("h", "k", ..., "z")

val a = A(...)
a.h.k.....z = "new value"

var  curItem: Any =  A(...)
for (itemName in breadCrumb){
    ...
    for(dataField in curItem::class.java.fields) {
        if(dataField.get(curItem).name == itemName){
           when(dataField.type.simpleName){
              "String" -> dataField .set(curItem, value.text)
              "Integer" -> dataField .setInt(curItem, value.text as Int)
              "Float" -> dataField .setFloat(curItem, value.text as Float)
              "Boolean" -> dataField .setBoolean(curItem, value.text as Boolean)
          }
          ..........
          curItem = dataField.java.get(curItem)
        }
    }
}

fun setValue(field: JSONUIField, value: JSONUIValue) {
    var curItem: Any = A.getAsJsonObject("a")

    for (itemName in breadCrumb) {
        if ((curItem as JsonObject).getAsJsonObject(itemName) == null)
            curItem.add(itemName, JsonObject())
        curItem = curItem.getAsJsonObject(itemName)
    }
    when (field.type) {
        "String" -> (curItem as JsonObject).addProperty(field.name, value.value)
        "Integer" -> (curItem as JsonObject).addProperty(field.name, (value.value)!!.toInt())
        "Float" -> (curItem as JsonObject).addProperty(field.name, (value.value)!!.toFloat())
        "Boolean" -> (curItem as JsonObject).addProperty(field.name, (value.value)!!.toBoolean())
    }
}

val curItem =  A("", false, 0)

val itemNames = listOf("a", "b", "c")
val itemStrValue = "test"
val itemIntValue = "10"
val itemFloatValue = "5.0"
val itemBooleanValue = "true"

for(dataField in curItem::class.declaredMemberProperties) {
    for (itemName in itemNames) {
        if (dataField.name == itemName) {
            val mutableProp = dataField as? KMutableProperty1<Any, Any>
            if (mutableProp != null) {
                when (dataField.returnType.classifier as KClass<Any>) {
                    String::class -> mutableProp.set(curItem, itemStrValue)
                    Int::class -> mutableProp.set(curItem, itemIntValue.toInt())
                    Float::class -> mutableProp.set(curItem, itemFloatValue.toFloat())
                    Boolean::class -> mutableProp.set(curItem, itemBooleanValue.toBoolean())
                }
            }
        }
    }
}

println(curItem) // A(a=test, b=true, c=10)

data class A(
    var a: String?,
    var b: Boolean?,
    var c: Int?
)