convert #36466 to kotlin

Author: stephane-airbyte

airbyte-cdk/java/airbyte-cdk/db-destinations/src/main/kotlin/io/airbyte/cdk/integrations/destination/jdbc/typing_deduping/JdbcDestinationHandler.kt

@@ -22,6 +22,7 @@ import java.time.Instant
 import java.time.OffsetDateTime
 import java.time.temporal.ChronoUnit
 import java.util.*
+import java.util.HashMap
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.CompletionStage
 import java.util.function.Predicate
@@ -254,12 +255,18 @@ abstract class JdbcDestinationHandler<DestinationState>(
                     // This is to handle any destinations that upcase the column names.
                     // For example - Snowflake with QUOTED_IDENTIFIERS_IGNORE_CASE=TRUE.
                     val record = recordJson as ObjectNode
-                    record.fieldNames().forEachRemaining { fieldName: String ->
-                        record.set<JsonNode>(
-                            fieldName.lowercase(Locale.getDefault()),
-                            record[fieldName]
-                        )
+                    val newFields: HashMap<String, JsonNode> = HashMap()
+
+                    val it = record.fieldNames()
+                    while (it.hasNext()) {
+                        val fieldName = it.next()
+                        // We can't directly call record.set here, because that will raise a
+                        // ConcurrentModificationException on the fieldnames iterator.
+                        // Instead, build up a map of new fields and set them all at once.
+                        newFields.put(fieldName.lowercase(Locale.getDefault()), record[fieldName])
                     }
+
+                    record.setAll<JsonNode>(newFields)
                 }
                 .collect(
                     toMap(