Retain type-use annotations such as @Nullable in generated builder …

…setters.

This handles a further case using the logic introduced by #1704.

RELNOTES=Type-use annotations such as `@Nullable` are now better preserved in generated builder setter method parameters. Previously they could be lost in some circumstances, for example with `@Nullable T`.
PiperOrigin-RevId: 699982315

value/src/main/java/com/google/auto/value/processor/BuilderMethodClassifier.java

@@ -402,8 +402,8 @@ private void classifyMethodOneArg(ExecutableElement method) {
                       + " is not appropriate", autoWhat());
         }
         // We allow the return type to be a supertype (other than Object), to support step builders.
-        TypeMirror parameterType =
-            Iterables.getOnlyElement(methodSignature.parameterTypes()).getType();
+        AnnotatedTypeMirror parameterType =
+            Iterables.getOnlyElement(methodSignature.parameterTypes());
         propertyNameToSetters.put(
             propertyName, new PropertySetter(method, parameterType, function.get()));
       } else {

value/src/main/java/com/google/auto/value/processor/BuilderSpec.java

@@ -462,25 +462,27 @@ public static class PropertySetter {
     private final String nullableAnnotation;
     private final Copier copier;
 
-    PropertySetter(ExecutableElement setter, TypeMirror parameterType, Copier copier) {
+    PropertySetter(ExecutableElement setter, AnnotatedTypeMirror parameterType, Copier copier) {
       this.setter = setter;
       this.copier = copier;
       this.access = SimpleMethod.access(setter);
       this.name = setter.getSimpleName().toString();
       primitiveParameter = parameterType.getKind().isPrimitive();
       this.parameterTypeString = parameterTypeString(setter, parameterType);
       VariableElement parameterElement = Iterables.getOnlyElement(setter.getParameters());
-      Optional<String> maybeNullable = nullableAnnotationFor(parameterElement, parameterType);
+      Optional<String> maybeNullable =
+          nullableAnnotationFor(parameterElement, parameterType.getType());
       this.nullableAnnotation = maybeNullable.orElse("");
     }
 
     ExecutableElement getSetter() {
       return setter;
     }
 
-    private static String parameterTypeString(ExecutableElement setter, TypeMirror parameterType) {
+    private static String parameterTypeString(
+        ExecutableElement setter, AnnotatedTypeMirror parameterType) {
       if (setter.isVarArgs()) {
-        TypeMirror componentType = MoreTypes.asArray(parameterType).getComponentType();
+        TypeMirror componentType = MoreTypes.asArray(parameterType.getType()).getComponentType();
         // This is a bit ugly. It's OK to annotate just the component type, because if it is
         // say `@Nullable String` then we will end up with `@Nullable String...`. Unlike the
         // normal array case, we can't have the situation where the array itself is annotated;

value/src/test/java/com/google/auto/value/processor/AutoBuilderCompilationTest.java

@@ -167,6 +167,40 @@ public void simpleRecord() {
         .hasSourceEquivalentTo(EXPECTED_SIMPLE_OUTPUT);
   }
 
+  @Test
+  public void recordWithNullableTypeVariableComponents() {
+    double version = Double.parseDouble(JAVA_SPECIFICATION_VERSION.value());
+    assume().that(version).isAtLeast(16.0);
+    JavaFileObject javaFileObject =
+        JavaFileObjects.forSourceLines(
+            "foo.bar.Baz",
+            "package foo.bar;",
+            "",
+            "import com.google.auto.value.AutoBuilder;",
+            "import org.checkerframework.checker.nullness.qual.Nullable;",
+            "",
+            "public record Baz<T>(int anInt, @Nullable T aT) {",
+            "  public static Builder builder() {",
+            "    return new AutoBuilder_Baz_Builder();",
+            "  }",
+            "",
+            "  @AutoBuilder",
+            "  public interface Builder<T> {",
+            "    Builder setAnInt(int x);",
+            "    Builder setAT(@Nullable T x);",
+            "    Baz<T> build();",
+            "  }",
+            "}");
+    Compilation compilation =
+        javac()
+            .withProcessors(new AutoBuilderProcessor())
+            .compile(javaFileObject);
+    assertThat(compilation)
+        .generatedSourceFile("foo.bar.AutoBuilder_Baz_Builder")
+        .contentsAsUtf8String()
+        .contains("public Baz.Builder<T> setAT(@Nullable T aT) {");
+  }
+
   @Test
   public void recordWithNullableNestedComponentType() {
     double version = Double.parseDouble(JAVA_SPECIFICATION_VERSION.value());