feat(gapic-generator): add JSpecify Null annotations to the generator classes

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/Main.java

@@ -21,13 +21,16 @@
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorRequest;
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorResponse;
 import java.io.IOException;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
+@NullMarked
 public class Main {
   public static void main(String[] args) throws IOException {
     ExtensionRegistry registry = ExtensionRegistry.newInstance();
     ProtoRegistry.registerAllExtensions(registry);
     CodeGeneratorRequest request = CodeGeneratorRequest.parseFrom(System.in, registry);
-    CodeGeneratorResponse response = Generator.generateGapic(request);
+    @Nullable CodeGeneratorResponse response = Generator.generateGapic(request);
     if (response != EMPTY_RESPONSE) {
       response.writeTo(System.out);
     }

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/ProtoRegistry.java

@@ -23,7 +23,9 @@
 import com.google.cloud.ExtendedOperationsProto;
 import com.google.longrunning.OperationsProto;
 import com.google.protobuf.ExtensionRegistry;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 public class ProtoRegistry {
   /** Register all extensions needed to process API protofiles. */
   public static void registerAllExtensions(ExtensionRegistry extensionRegistry) {

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/debug/CodeGeneratorRequestDumper.java

@@ -19,12 +19,14 @@
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorRequest;
 import com.google.protobuf.compiler.PluginProtos.CodeGeneratorResponse;
 import java.io.IOException;
+import org.jspecify.annotations.NullMarked;
 
 // Request dumper class, which dumps the CodeGeneratorRequest to a file on disk which will be
 // identical to the one passed to the Main class during normal execution. The dumped file then can
 // be used to run this gapic-generator directly (instead of relying on protoc to start the process),
 // which would give much greater flexibility in terms of debugging features, like attaching a
 // debugger, easier work with stdout and stderr etc.
+@NullMarked
 public class CodeGeneratorRequestDumper {
   public static void main(String[] args) throws IOException {
     ExtensionRegistry registry = ExtensionRegistry.newInstance();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/debug/CodeGeneratorRequestFileToGapicMain.java

@@ -24,9 +24,12 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
 // A generator entry point class, similar to Main but reads the CodeGeneratorRequest directly from a
 // file instead of relying on protoc to pipe it in.
+@NullMarked
 public class CodeGeneratorRequestFileToGapicMain {
   public static void main(String[] args) throws IOException {
     ExtensionRegistry registry = ExtensionRegistry.newInstance();
@@ -38,7 +41,7 @@ public static void main(String[] args) throws IOException {
     try (InputStream inputStream = new FileInputStream(inputFile);
         OutputStream outputStream = new FileOutputStream(outputFile)) {
       CodeGeneratorRequest request = CodeGeneratorRequest.parseFrom(inputStream, registry);
-      CodeGeneratorResponse response = Generator.generateGapic(request);
+      @Nullable CodeGeneratorResponse response = Generator.generateGapic(request);
       response.writeTo(outputStream);
     }
   }

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/AnnotationNode.java

@@ -19,8 +19,10 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import javax.annotation.Nullable;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
+@NullMarked
 @AutoValue
 public abstract class AnnotationNode implements AstNode {
   public static AnnotationNode OVERRIDE =
@@ -34,8 +36,7 @@
 
   public abstract TypeNode type();
 
-  @Nullable
-  public abstract List<Expr> descriptionExprs();
+  public abstract @Nullable List<Expr> descriptionExprs();
 
   @Override
   public void accept(AstNodeVisitor visitor) {
@@ -138,7 +139,7 @@
       List<Expr> exprList = descriptionExprs();
       // avoid when single parameter is already set.
       Preconditions.checkState(
           exprList == null || exprList instanceof ArrayList,
           MULTIPLE_AFTER_SINGLE_EXCEPTION_MESSAGE);
       if (exprList == null) {
         exprList = new ArrayList<>();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/AnonymousClassExpr.java

@@ -20,7 +20,9 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class AnonymousClassExpr implements Expr {
   @Override

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/ArithmeticOperationExpr.java

@@ -16,7 +16,9 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class ArithmeticOperationExpr implements OperationExpr {
 

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/ArrayExpr.java

@@ -19,7 +19,9 @@
 import com.google.common.collect.ImmutableList;
 import java.util.Arrays;
 import java.util.List;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class ArrayExpr implements Expr {
 

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/AssignmentExpr.java

@@ -16,7 +16,9 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class AssignmentExpr implements Expr {
   public abstract VariableExpr variableExpr();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/AssignmentOperationExpr.java

@@ -16,7 +16,9 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class AssignmentOperationExpr implements OperationExpr {
   public abstract VariableExpr variableExpr();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/AstNode.java

@@ -14,6 +14,9 @@
 
 package com.google.api.generator.engine.ast;
 
+import org.jspecify.annotations.NullMarked;
+
+@NullMarked
 public interface AstNode {
   /** Writes the syntatically-correct Java code representation of this node. */
   public void accept(AstNodeVisitor visitor);

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/AstNodeVisitor.java

@@ -14,6 +14,9 @@
 
 package com.google.api.generator.engine.ast;
 
+import org.jspecify.annotations.NullMarked;
+
+@NullMarked
 public interface AstNodeVisitor {
   /** Writes the syntatically-correct Java code representation of this node. */
   public void visit(IdentifierNode identifier);

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/BlockComment.java

@@ -15,7 +15,9 @@
 package com.google.api.generator.engine.ast;
 
 import com.google.auto.value.AutoValue;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class BlockComment implements Comment {
   @Override

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/BlockStatement.java

@@ -17,7 +17,9 @@
 import com.google.auto.value.AutoValue;
 import com.google.common.collect.ImmutableList;
 import java.util.List;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class BlockStatement implements Statement {
   // TODO(unsupported): Named blocks.

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/BreakStatement.java

@@ -14,6 +14,9 @@
 
 package com.google.api.generator.engine.ast;
 
+import org.jspecify.annotations.NullMarked;
+
+@NullMarked
 public class BreakStatement implements Statement {
   private BreakStatement() {}
 

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/CastExpr.java

@@ -16,7 +16,9 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class CastExpr implements Expr {
   @Override

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/ClassDefinition.java

@@ -21,16 +21,17 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
-import javax.annotation.Nullable;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
+@NullMarked
 @AutoValue
 public abstract class ClassDefinition implements AstNode {
   // Optional.
   public abstract ImmutableList<CommentStatement> fileHeader();
 
   // Required for samples classes.
-  @Nullable
-  public abstract RegionTag regionTag();
+  public abstract @Nullable RegionTag regionTag();
 
   // Required.
   public abstract ScopeNode scope();
@@ -39,8 +40,7 @@ public abstract class ClassDefinition implements AstNode {
   public abstract IdentifierNode classIdentifier();
 
   // Required for outer classes.
-  @Nullable
-  public abstract String packageString();
+  public abstract @Nullable String packageString();
 
   public abstract boolean isNested();
 
@@ -52,8 +52,7 @@ public abstract class ClassDefinition implements AstNode {
   // Using a list helps with determinism in unit tests.
   public abstract ImmutableList<TypeNode> implementsTypes();
 
-  @Nullable
-  public abstract TypeNode extendsType();
+  public abstract @Nullable TypeNode extendsType();
 
   public abstract boolean isStatic();
 

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/Comment.java

@@ -14,6 +14,9 @@
 
 package com.google.api.generator.engine.ast;
 
+import org.jspecify.annotations.NullMarked;
+
+@NullMarked
 public interface Comment {
   public String comment();
 

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/CommentStatement.java

@@ -15,7 +15,9 @@
 package com.google.api.generator.engine.ast;
 
 import com.google.auto.value.AutoValue;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class CommentStatement implements Statement {
   public abstract Comment comment();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/ConcreteReference.java

@@ -19,8 +19,10 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Objects;
-import javax.annotation.Nullable;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
+@NullMarked
 @AutoValue
 public abstract class ConcreteReference implements Reference {
   private static final String EXTENDS = "extends";
@@ -152,7 +154,7 @@
   @Override
   public boolean isAssignableFrom(Reference other) {
     if (other instanceof VaporReference && ((VaporReference) other).supertypeReference() != null) {
       return isAssignableFrom(((VaporReference) other).supertypeReference());
     }
 
     if (!(other instanceof ConcreteReference)) {
@@ -176,7 +178,7 @@
   }
 
   @Override
-  public boolean equals(Object o) {
+  public boolean equals(@Nullable Object o) {
     if (!(o instanceof ConcreteReference)) {
       return false;
     }

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/EmptyLineStatement.java

@@ -14,6 +14,9 @@
 
 package com.google.api.generator.engine.ast;
 
+import org.jspecify.annotations.NullMarked;
+
+@NullMarked
 public class EmptyLineStatement implements Statement {
   private EmptyLineStatement() {}
 

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/EnumRefExpr.java

@@ -16,7 +16,9 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class EnumRefExpr implements Expr {
   public abstract IdentifierNode identifier();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/Expr.java

@@ -14,6 +14,9 @@
 
 package com.google.api.generator.engine.ast;
 
+import org.jspecify.annotations.NullMarked;
+
+@NullMarked
 public interface Expr extends AstNode {
   TypeNode type();
 

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/ExprStatement.java

@@ -16,7 +16,9 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class ExprStatement implements Statement {
   public abstract Expr expression();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/ForStatement.java

@@ -18,7 +18,9 @@
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import java.util.List;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class ForStatement implements Statement {
   public abstract VariableExpr localVariableExpr();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/GeneralForStatement.java

@@ -19,7 +19,9 @@
 import com.google.common.collect.ImmutableList;
 import java.util.Collections;
 import java.util.List;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class GeneralForStatement implements Statement {
   public abstract Expr initializationExpr();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/IdentifierNode.java

@@ -22,7 +22,9 @@
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
 import java.util.regex.Pattern;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class IdentifierNode implements AstNode {
   static class InvalidIdentifierException extends RuntimeException {

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/IfStatement.java

@@ -20,7 +20,9 @@
 import com.google.common.collect.ImmutableMap;
 import java.util.Collections;
 import java.util.List;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class IfStatement implements Statement {
   public abstract Expr conditionExpr();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/InstanceofExpr.java

@@ -16,7 +16,9 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
+import org.jspecify.annotations.NullMarked;
 
+@NullMarked
 @AutoValue
 public abstract class InstanceofExpr implements Expr {
   public abstract Expr expr();

sdk-platform-java/gapic-generator-java/src/main/java/com/google/api/generator/engine/ast/JavaDocComment.java

@@ -23,7 +23,10 @@
 import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
+@NullMarked
 @AutoValue
 public abstract class JavaDocComment implements Comment {
   @Override
@@ -48,11 +51,11 @@ public abstract static class Builder {
     static final String PARAM_INDENT = "       ";
 
     // The lack of a getter for these local variables in the external class is WAI.
-    String throwsType = null;
-    String throwsDescription = null;
-    String deprecated = null;
-    String internalOnly = null;
-    String returnDescription = null;
+    @Nullable String throwsType = null;
+    @Nullable String throwsDescription = null;
+    @Nullable String deprecated = null;
+    @Nullable String internalOnly = null;
+    @Nullable String returnDescription = null;
     List<String> paramsList = new ArrayList<>();
     List<String> componentsList = new ArrayList<>();