diff --git a/.idea/misc.xml b/.idea/misc.xml
index 717f90a..4d16d9a 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,3 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
   <component name="ExternalStorageConfigurationManager" enabled="true" />
   <component name="MavenProjectsManager">
@@ -7,5 +8,5 @@
       </list>
     </option>
   </component>
-  <component name="ProjectRootManager" version="2" languageLevel="JDK_21" default="true" project-jdk-name="21" project-jdk-type="JavaSDK" />
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_17" project-jdk-name="21" project-jdk-type="JavaSDK" />
 </project>
\ No newline at end of file
diff --git a/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/commands/ComputeRefactorEditHandler.java b/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/commands/ComputeRefactorEditHandler.java
index 0a122f7..b03bfaf 100644
--- a/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/commands/ComputeRefactorEditHandler.java
+++ b/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/commands/ComputeRefactorEditHandler.java
@@ -58,8 +58,8 @@ protected Object executeCommand(DOMDocument document, ExecuteCommandParams param
         }
         var edits = new ArrayList<Either<TextDocumentEdit, ResourceOperation>>();
 
-        var actualStartOffset = selectedNodes.getFirst().getStart();
-        var actualEndOffset = selectedNodes.getLast().getEnd();
+        var actualStartOffset = selectedNodes.get(0).getStart();
+        var actualEndOffset = selectedNodes.get(selectedNodes.size() - 1).getEnd();
 
         var text = document.getTextDocument().getText().substring(actualStartOffset, actualEndOffset);
         var targetEdit = computeTargetEdit(targetDocument, text);
diff --git a/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/participants/diagnostics/CfgEnvironmentDiagnosticsParticipant.java b/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/participants/diagnostics/CfgEnvironmentDiagnosticsParticipant.java
index 9c3d9d5..4be28d6 100644
--- a/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/participants/diagnostics/CfgEnvironmentDiagnosticsParticipant.java
+++ b/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/participants/diagnostics/CfgEnvironmentDiagnosticsParticipant.java
@@ -41,7 +41,7 @@ public void doDiagnostics(DOMDocument domDocument, List<Diagnostic> list, XMLVal
     }
 
     private void validateCfgEnvironment(DOMDocument document, List<Diagnostic> diagnostics) {
-        var territoriesNode = document.getDocumentElement().getChildren().getFirst();
+        var territoriesNode = document.getDocumentElement().getChildren().get(0);
         var fileNodes = territoriesNode.getChildren().stream()
                 .filter(n -> CfgEnvironmentModel.FILE_TAG.equals(n.getNodeName()))
                 .toList();
diff --git a/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/participants/diagnostics/MapGroupProtoDiagnosticsParticipant.java b/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/participants/diagnostics/MapGroupProtoDiagnosticsParticipant.java
index c1031a2..961bf1c 100644
--- a/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/participants/diagnostics/MapGroupProtoDiagnosticsParticipant.java
+++ b/lemminx-dayz-ce/src/main/java/io/github/rvost/lemminx/dayz/participants/diagnostics/MapGroupProtoDiagnosticsParticipant.java
@@ -40,7 +40,7 @@ private void validate(DOMDocument document, List<Diagnostic> diagnostics, Cancel
         var limitsDefinitions = missionService.getLimitsDefinitions();
         var userLimitDefinitions = missionService.getUserLimitsDefinitions();
 
-        var defaultsNode = document.getDocumentElement().getChildren().getFirst();
+        var defaultsNode = document.getDocumentElement().getChildren().get(0);
         defaultsNode.getChildren().stream()
                 .filter(n -> MapGroupProtoModel.DEFAULT_TAG.equals(n.getNodeName()))
                 .map(n -> n.getAttributeNode(MapGroupProtoModel.DE_ATTRIBUTE))