Remove private from generated Factory's INSTANCE field.

Fixes #4544

Background: Dagger's generated factory has an optimization to lazy load a singleton instance of the factory when there are no dependencies:

```
public final class Foo_Factory implements Factory<Foo> {
  public static Foo_Factory create() {
    return InstanceHolder.INSTANCE;
  }

  private static final class InstanceHolder {
    private static final Foo_Factory INSTANCE = new Foo_Factory();
  }
}
```

The `private` modifier on the `INSTANCE` field is not needed and can add extra overhead as described in #4544. Removing the `private` modifier is also needed once we start generating Kotlin sources since accessing a `private` field on a nested class in kotlin source is a kotlinc error.

RELNOTES=Fixes #4544: Removes private from InstanceHolder field.
PiperOrigin-RevId: 708101532

java/dagger/internal/codegen/base/SourceFileHjarGenerator.java

@@ -201,11 +201,16 @@ private static CodeBlock getDefaultValueCodeBlock(TypeName typeName) {
   }
 
   private FieldSpec skeletonField(FieldSpec completeField) {
-    return FieldSpec.builder(
-            completeField.type,
-            completeField.name,
-            completeField.modifiers.toArray(new Modifier[0]))
-        .addAnnotations(completeField.annotations)
-        .build();
+    FieldSpec.Builder skeleton =
+        FieldSpec.builder(
+                completeField.type,
+                completeField.name,
+                completeField.modifiers.toArray(new Modifier[0]))
+            .addAnnotations(completeField.annotations);
+    if (completeField.modifiers.contains(Modifier.FINAL)) {
+      // Final fields must be initialized so use the default value.
+      skeleton.initializer(getDefaultValueCodeBlock(completeField.type));
+    }
+    return skeleton.build();
   }
 }

java/dagger/internal/codegen/writing/FactoryGenerator.java

@@ -159,13 +159,13 @@ private TypeSpec.Builder factoryBuilder(ContributionBinding binding) {
   }
 
   // private static final class InstanceHolder {
-  //   private static final FooModule_ProvidesFooFactory INSTANCE =
+  //   static final FooModule_ProvidesFooFactory INSTANCE =
   //       new FooModule_ProvidesFooFactory();
   // }
   private TypeSpec staticInstanceHolderType(ContributionBinding binding) {
     ClassName generatedClassName = generatedClassNameForBinding(binding);
     FieldSpec.Builder instanceHolderFieldBuilder =
-        FieldSpec.builder(generatedClassName, "INSTANCE", PRIVATE, STATIC, FINAL)
+        FieldSpec.builder(generatedClassName, "INSTANCE", STATIC, FINAL)
             .initializer("new $T()", generatedClassName);
     if (!bindingTypeElementTypeVariableNames(binding).isEmpty()) {
       // If the factory has type parameters, ignore them in the field declaration & initializer

javatests/dagger/internal/codegen/goldens/ComponentProcessorTest_nullCheckingIgnoredWhenProviderReturnsPrimitive_DEFAULT_MODE_test.TestModule_PrimitiveIntegerFactory

@@ -37,7 +37,7 @@ public final class TestModule_PrimitiveIntegerFactory implements Factory<Integer
   }
 
   private static final class InstanceHolder {
-    private static final TestModule_PrimitiveIntegerFactory INSTANCE = new TestModule_PrimitiveIntegerFactory();
+    static final TestModule_PrimitiveIntegerFactory INSTANCE = new TestModule_PrimitiveIntegerFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ComponentProcessorTest_nullCheckingIgnoredWhenProviderReturnsPrimitive_FAST_INIT_MODE_test.TestModule_PrimitiveIntegerFactory

@@ -37,7 +37,7 @@ public final class TestModule_PrimitiveIntegerFactory implements Factory<Integer
   }
 
   private static final class InstanceHolder {
-    private static final TestModule_PrimitiveIntegerFactory INSTANCE = new TestModule_PrimitiveIntegerFactory();
+    static final TestModule_PrimitiveIntegerFactory INSTANCE = new TestModule_PrimitiveIntegerFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ComponentProcessorTest_nullIncorrectlyReturnedFromNonNullableInlinedProvider_DEFAULT_MODE_test.TestModule_NonNullableStringFactory

@@ -38,7 +38,7 @@ public final class TestModule_NonNullableStringFactory implements Factory<String
   }
 
   private static final class InstanceHolder {
-    private static final TestModule_NonNullableStringFactory INSTANCE = new TestModule_NonNullableStringFactory();
+    static final TestModule_NonNullableStringFactory INSTANCE = new TestModule_NonNullableStringFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ComponentProcessorTest_nullIncorrectlyReturnedFromNonNullableInlinedProvider_FAST_INIT_MODE_test.TestModule_NonNullableStringFactory

@@ -38,7 +38,7 @@ public final class TestModule_NonNullableStringFactory implements Factory<String
   }
 
   private static final class InstanceHolder {
-    private static final TestModule_NonNullableStringFactory INSTANCE = new TestModule_NonNullableStringFactory();
+    static final TestModule_NonNullableStringFactory INSTANCE = new TestModule_NonNullableStringFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/InjectConstructorFactoryGeneratorTest_genericClassWithNoDependencies_test.GenericClass_Factory

@@ -39,7 +39,7 @@ public final class GenericClass_Factory<T> implements Factory<GenericClass<T>> {
 
   private static final class InstanceHolder {
     @SuppressWarnings("rawtypes")
-    private static final GenericClass_Factory INSTANCE = new GenericClass_Factory();
+    static final GenericClass_Factory INSTANCE = new GenericClass_Factory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/InjectConstructorFactoryGeneratorTest_noDeps_test.SimpleType_Factory

@@ -37,7 +37,7 @@ public final class SimpleType_Factory implements Factory<SimpleType> {
   }
 
   private static final class InstanceHolder {
-    private static final SimpleType_Factory INSTANCE = new SimpleType_Factory();
+    static final SimpleType_Factory INSTANCE = new SimpleType_Factory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/InjectConstructorFactoryGeneratorTest_simpleComponentWithNesting_test.OuterType_A_Factory

@@ -37,7 +37,7 @@ public final class OuterType_A_Factory implements Factory<OuterType.A> {
   }
 
   private static final class InstanceHolder {
-    private static final OuterType_A_Factory INSTANCE = new OuterType_A_Factory();
+    static final OuterType_A_Factory INSTANCE = new OuterType_A_Factory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/InjectConstructorFactoryGeneratorTest_testScopedMetadataWithCustomScope_test.ScopedBinding_Factory

@@ -37,7 +37,7 @@ public final class ScopedBinding_Factory implements Factory<ScopedBinding> {
   }
 
   private static final class InstanceHolder {
-    private static final ScopedBinding_Factory INSTANCE = new ScopedBinding_Factory();
+    static final ScopedBinding_Factory INSTANCE = new ScopedBinding_Factory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/InjectConstructorFactoryGeneratorTest_testScopedMetadata_test.ScopedBinding_Factory

@@ -37,7 +37,7 @@ public final class ScopedBinding_Factory implements Factory<ScopedBinding> {
   }
 
   private static final class InstanceHolder {
-    private static final ScopedBinding_Factory INSTANCE = new ScopedBinding_Factory();
+    static final ScopedBinding_Factory INSTANCE = new ScopedBinding_Factory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ModuleFactoryGeneratorTest_parameterizedModuleWithStaticProvidesMethodOfGenericType_test.ParameterizedModule_ProvideMapStringNumberFactory

@@ -39,7 +39,7 @@ public final class ParameterizedModule_ProvideMapStringNumberFactory implements
   }
 
   private static final class InstanceHolder {
-    private static final ParameterizedModule_ProvideMapStringNumberFactory INSTANCE = new ParameterizedModule_ProvideMapStringNumberFactory();
+    static final ParameterizedModule_ProvideMapStringNumberFactory INSTANCE = new ParameterizedModule_ProvideMapStringNumberFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ModuleFactoryGeneratorTest_parameterizedModuleWithStaticProvidesMethodOfGenericType_test.ParameterizedModule_ProvideNonGenericTypeFactory

@@ -38,7 +38,7 @@ public final class ParameterizedModule_ProvideNonGenericTypeFactory implements F
   }
 
   private static final class InstanceHolder {
-    private static final ParameterizedModule_ProvideNonGenericTypeFactory INSTANCE = new ParameterizedModule_ProvideNonGenericTypeFactory();
+    static final ParameterizedModule_ProvideNonGenericTypeFactory INSTANCE = new ParameterizedModule_ProvideNonGenericTypeFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ModuleFactoryGeneratorTest_proxyMethodsConflictWithOtherFactoryMethods_test.TestModule_CreateFactory

@@ -37,7 +37,7 @@ public final class TestModule_CreateFactory implements Factory<Boolean> {
   }
 
   private static final class InstanceHolder {
-    private static final TestModule_CreateFactory INSTANCE = new TestModule_CreateFactory();
+    static final TestModule_CreateFactory INSTANCE = new TestModule_CreateFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ModuleFactoryGeneratorTest_proxyMethodsConflictWithOtherFactoryMethods_test.TestModule_GetFactory

@@ -37,7 +37,7 @@ public final class TestModule_GetFactory implements Factory<Integer> {
   }
 
   private static final class InstanceHolder {
-    private static final TestModule_GetFactory INSTANCE = new TestModule_GetFactory();
+    static final TestModule_GetFactory INSTANCE = new TestModule_GetFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ModuleFactoryGeneratorTest_testScopeMetadataWithCustomScope_test.MyModule_ProvideStringFactory

@@ -38,7 +38,7 @@ public final class MyModule_ProvideStringFactory implements Factory<String> {
   }
 
   private static final class InstanceHolder {
-    private static final MyModule_ProvideStringFactory INSTANCE = new MyModule_ProvideStringFactory();
+    static final MyModule_ProvideStringFactory INSTANCE = new MyModule_ProvideStringFactory();
   }
 }
 

javatests/dagger/internal/codegen/goldens/ModuleFactoryGeneratorTest_testScopedMetadataOnStaticProvides_test.MyModule_ProvideStringFactory

@@ -38,7 +38,7 @@ public final class MyModule_ProvideStringFactory implements Factory<String> {
   }
 
   private static final class InstanceHolder {
-    private static final MyModule_ProvideStringFactory INSTANCE = new MyModule_ProvideStringFactory();
+    static final MyModule_ProvideStringFactory INSTANCE = new MyModule_ProvideStringFactory();
   }
 }