possible fix

org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/LanguageUtils.java

@@ -296,7 +296,10 @@ public class LanguageUtils {
         }
       }
     }
-    for (Element c : element.getChildren()) {
+
+    // Create a copy of the children collection before iterating
+    List<Element> childrenCopy = new ArrayList<>(element.getChildren());
+    for (Element c : childrenCopy) {
       if (!c.getName().equals("designation")) {
         t = t + importFromTranslations(element, c, translations, usedUnits);
       }

org.hl7.fhir.r5/src/test/java/org/hl7/fhir/r5/elementmodel/LanguageUtilsTest.java

@@ -1,15 +1,20 @@
 package org.hl7.fhir.r5.elementmodel;
 
 import org.hl7.fhir.r5.context.IWorkerContext;
+import org.hl7.fhir.r5.formats.JsonCreatorDirect;
+import org.hl7.fhir.r5.test.utils.CompareUtilities;
 import org.hl7.fhir.r5.test.utils.TestingUtilities;
 import org.hl7.fhir.utilities.i18n.LanguageFileProducer;
 import org.hl7.fhir.utilities.i18n.PoGetTextProducer;
 import org.hl7.fhir.utilities.tests.ResourceLoaderTests;
+import org.hl7.fhir.utilities.validation.ValidationMessage;
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
-import java.io.InputStream;
+import java.io.*;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 
 class LanguageUtilsTest implements ResourceLoaderTests {
@@ -27,11 +32,24 @@ class LanguageUtilsTest implements ResourceLoaderTests {
     List<LanguageFileProducer.TranslationUnit> res = new ArrayList<>();
     res.addAll(lp.loadSource(getResourceAsInputStream("languageUtils", "CodeSystem-answer.po")));
 
+    List<ValidationMessage> lvm = new ArrayList<>();
+    lvm.add(new ValidationMessage());
     LanguageUtils languageUtils = new LanguageUtils(context);
-    int result = languageUtils.importFromTranslations(element, res, null);
+    int result = languageUtils.importFromTranslations(element, res, lvm);
+
+    Writer generatedResource = new StringWriter();
+    jp.compose(element, new JsonCreatorDirect(generatedResource, false, false));
 
     assert result == 3;
 
+    InputStream translatedResource = getResourceAsInputStream("languageUtils", "CodeSystem-answer-translated.json");
+    String text = new BufferedReader(new InputStreamReader(translatedResource))
+      .lines()
+      .collect(Collectors.joining("\n"));
+
+    String msg = CompareUtilities.checkJsonSrcIsSame("", generatedResource.toString(),text, null);
+    Assertions.assertNull(msg);
+
   }
 
 }

org.hl7.fhir.r5/src/test/resources/languageUtils/CodeSystem-answer-translated.json

@@ -0,0 +1,38 @@
+{
+  "resourceType" : "CodeSystem",
+  "id" : "basic-answer",
+  "language" : "en",
+  "url" : "https://example.com/CodeSystem/basic-answer",
+  "version" : "0.1.0",
+  "name" : "BasicAnswer",
+  "title" : "Administration-Method",
+  "status" : "active",
+  "date" : "2024-04-07",
+  "publisher" : "Sample",
+  "description" : "Basic answers for any kind of questions.",
+  "caseSensitive" : false,
+  "content" : "complete",
+  "count" : 3,
+  "concept" : [ {
+    "code" : "ok",
+    "display" : "OK",
+    "designation" : [ {
+      "language" : "it",
+      "value" : "OK"
+    } ]
+  }, {
+    "code" : "yes",
+    "display" : "Yes",
+    "designation" : [ {
+      "language" : "it",
+      "value" : "Si"
+    } ]
+  }, {
+    "code" : "no",
+    "display" : "No",
+    "designation" : [ {
+      "language" : "it",
+      "value" : "No"
+    } ]
+  } ]
+}

org.hl7.fhir.r5/src/test/resources/languageUtils/CodeSystem-answer.json

@@ -10,18 +10,15 @@
   "concept": [
     {
       "code": "ok",
-      "display": "OK",
-      "definition": "KO"
+      "display": "OK"
     },
     {
       "code": "yes",
-      "display": "Yes",
-      "definition": "seY"
+      "display": "Yes"
     },
     {
       "code": "no",
-      "display": "No",
-      "definition": "oN"
+      "display": "No"
     }
   ],
   "language": "en",