fix testcases and transformer

Author: wadoon

key.core/src/main/java/de/uka/ilkd/key/java/transformations/pipeline/MultiCatchReducer.java

@@ -3,6 +3,7 @@
  * SPDX-License-Identifier: GPL-2.0-only */
 package de.uka.ilkd.key.java.transformations.pipeline;
 
+import com.github.javaparser.ast.Modifier;
 import com.github.javaparser.ast.body.TypeDeclaration;
 import com.github.javaparser.ast.stmt.CatchClause;
 import com.github.javaparser.ast.stmt.TryStmt;
@@ -23,11 +24,11 @@
 /// ```java
 /// try {
 /// body
-/// } catch (ExceptionType1 e) {
+/// } catch (final ExceptionType1 e) {
 /// handler
-/// } catch (ExceptionType2 e) {
+/// } catch (final ExceptionType2 e) {
 /// handler
-/// } catch (ExceptionType3 e) {
+/// } catch (final ExceptionType3 e) {
 /// handler
 /// }
 /// ```
@@ -54,39 +55,33 @@ public void apply(TypeDeclaration<?> td) {
      */
     private void rewrite(TryStmt tryStmt) {
         var catchClauses = tryStmt.getCatchClauses();
-
-        // Process catch clauses in reverse order to safely modify the list while iterating
-        for (int i = catchClauses.size() - 1; i >= 0; i--) {
-            CatchClause catchClause = catchClauses.get(i);
+        var originalClauses = catchClauses.stream().toList();
+        for (int i = 0; i < originalClauses.size(); i++) {
+            CatchClause catchClause = originalClauses.get(i);
             var paramType = catchClause.getParameter().getType();
-
-            if (paramType instanceof UnionType) {
-                UnionType unionType = (UnionType) paramType;
+            if (paramType instanceof UnionType unionType) {
+                catchClauses.remove(i); // delete original clause
+                int j = i;
 
                 // Create individual catch clauses for each exception type in the union
                 for (var elementType : unionType.getElements()) {
                     CatchClause newCatchClause = new CatchClause();
-
                     // Create a new parameter with the single exception type
                     var originalParam = catchClause.getParameter();
                     var newParam = new com.github.javaparser.ast.body.Parameter(
                         elementType.clone(),
                         originalParam.getName().clone());
 
                     // Copy modifiers (the parameter is implicitly final in multi-catch)
-                    newParam.addFinalModifier();
-
+                    newParam.addModifier(Modifier.DefaultKeyword.FINAL);
                     newCatchClause.setParameter(newParam);
 
                     // Clone the body for each catch clause
                     newCatchClause.setBody(catchClause.getBody().clone());
 
                     // Insert after the current position (will be before due to reverse iteration)
-                    catchClauses.add(i + 1, newCatchClause);
+                    catchClauses.add(j++, newCatchClause);
                 }
-
-                // Remove the original multi-catch clause
-                catchClauses.remove(i);
             }
         }
     }

key.core/src/test/java/de/uka/ilkd/key/java/transformations/pipeline/MultiCatchReducerTest.java

@@ -42,9 +42,9 @@ class Demo {
                     void run() {
                         try {
                             doSomething();
-                        } catch (Exception1 e) {
+                        } catch (final Exception1 e) {
                             System.out.println("caught: " + e);
-                        } catch (Exception2 e) {
+                        } catch (final Exception2 e) {
                             System.out.println("caught: " + e);
                         }
                     }
@@ -84,11 +84,11 @@ class Demo {
                     void run() {
                         try {
                             doSomething();
-                        } catch (IOException e) {
+                        } catch (final IOException e) {
                             handle(e);
-                        } catch (SQLException e) {
+                        } catch (final SQLException e) {
                             handle(e);
-                        } catch (RuntimeException e) {
+                        } catch (final RuntimeException e) {
                             handle(e);
                         }
                     }
@@ -137,9 +137,9 @@ void run() {
                             doSomething();
                         } catch (IllegalArgumentException e) {
                             log("illegal arg");
-                        } catch (IOException e) {
+                        } catch (final IOException e) {
                             log("io/sql error");
-                        } catch (SQLException e) {
+                        } catch (final SQLException e) {
                             log("io/sql error");
                         } catch (RuntimeException e) {
                             throw e;
@@ -187,9 +187,9 @@ class Demo {
                     void run() {
                         try {
                             doSomething();
-                        } catch (Exception1 e) {
+                        } catch (final Exception1 e) {
                             handle(e);
-                        } catch (Exception2 e) {
+                        } catch (final Exception2 e) {
                             handle(e);
                         } finally {
                             cleanup();