Require modifier initialization for extends setting

Author: liach

test/langtools/jdk/javadoc/doclet/testSerializedFormWithClassFile/TestSerializedFormWithClassFile.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -106,8 +106,8 @@ void createTestClass(Path base, Path srcDir) throws Exception {
         new JavacTask(tb).files(srcDir.resolve("A.java")).outdir(classes).run();
 
         new ClassBuilder(tb, "B")
-                .setExtends("A")
                 .setModifiers("public", "class")
+                .setExtends("A")
                 .write(srcDir);
     }
 }

test/langtools/jdk/javadoc/doclet/testVisibleMembers/TestVisibleMembers.java

@@ -677,8 +677,8 @@ void emitHiddenMembers(Path srcDir) throws Exception {
                 .write(srcDir);
 
         new ClassBuilder(tb, "p.C2")
-                .setExtends("C1")
                 .setModifiers("public", "abstract", "class")
+                .setExtends("C1")
                 .addMembers(
                         FieldBuilder.parse("public int field;"),
                         MethodBuilder.parse("public void method(){}"),

test/langtools/tools/lib/builder/AbstractBuilder.java

@@ -204,7 +204,10 @@ public void setModifiers(List<String> modifiers) {
         }
 
         boolean isInterface() {
-            return !modifiers.isEmpty() && modifiers.getLast().endsWith("interface");
+            if (modifiers.isEmpty()) {
+                throw new IllegalStateException("modifiers not initialized");
+            }
+            return modifiers.getLast().endsWith("interface");
         }
 
         @Override