Java: avoid infinite loop when creating switch branches for enum with duplicate constants (IDEA-357561)

GitOrigin-RevId: e9c84396786baceb58501a56d5d7e529f5ae9276

java/java-impl/src/com/siyeh/ig/fixes/CreateEnumMissingSwitchBranchesFix.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.siyeh.ig.fixes;
 
 import com.intellij.psi.*;
@@ -25,7 +25,7 @@ public final class CreateEnumMissingSwitchBranchesFix extends CreateMissingSwitc
 
   @Override
   protected @NotNull List<String> getAllNames(@NotNull PsiClass aClass, @NotNull PsiSwitchBlock switchBlock) {
-    return StreamEx.of(aClass.getAllFields()).select(PsiEnumConstant.class).map(PsiField::getName).toList();
+    return StreamEx.of(aClass.getFields()).select(PsiEnumConstant.class).map(PsiField::getName).distinct().toList();
   }
 
   @Override

java/java-tests/testData/ig/com/siyeh/igfixes/controlflow/enumswitch/afterDuplicateEnumConstant.java

@@ -0,0 +1,15 @@
+// "Create missing branches 'A', 'B', and 'C'" "true"
+class Main {
+  enum E {A, B, C, C}
+
+  public void f(E e) {
+    switch (e) {
+        case A -> {
+        }
+        case B -> {
+        }
+        case C -> {
+        }
+    }
+  }
+}

java/java-tests/testData/ig/com/siyeh/igfixes/controlflow/enumswitch/beforeDuplicateEnumConstant.java

@@ -0,0 +1,9 @@
+// "Create missing branches 'A', 'B', and 'C'" "true"
+class Main {
+  enum E {A, B, C, C}
+
+  public void f(E e) {
+    switch<caret> (e) {
+    }
+  }
+}