Breaking change: Lock down visibility for FileDescriptor.getSyntax().

Syntax will become meaningless once we migrate to editions.  In the meantime, we've implemented APIs to expose the differences between proto2 and proto3 in terms of the features we plan to release in edition 2023.

PiperOrigin-RevId: 520433607

Author: zhangskz

java/core/src/main/java/com/google/protobuf/Descriptors.java

@@ -162,7 +162,7 @@ public List<FileDescriptor> getPublicDependencies() {
     }
 
     /** The syntax of the .proto file. */
-    public enum Syntax {
+    enum Syntax {
       UNKNOWN("unknown"),
       PROTO2("proto2"),
       PROTO3("proto3");
@@ -175,7 +175,7 @@ public enum Syntax {
     }
 
     /** Get the syntax of the .proto file. */
-    public Syntax getSyntax() {
+    Syntax getSyntax() {
       if (Syntax.PROTO3.name.equals(proto.getSyntax())) {
         return Syntax.PROTO3;
       }

ruby/src/main/java/com/google/protobuf/jruby/RubyEnumDescriptor.java

@@ -35,7 +35,7 @@
 import com.google.protobuf.DescriptorProtos.EnumDescriptorProto;
 import com.google.protobuf.Descriptors.EnumDescriptor;
 import com.google.protobuf.Descriptors.EnumValueDescriptor;
-import com.google.protobuf.Descriptors.FileDescriptor;
+import com.google.protobuf.LegacyDescriptorsUtil.LegacyFileDescriptor;
 import org.jruby.Ruby;
 import org.jruby.RubyClass;
 import org.jruby.RubyModule;
@@ -160,7 +160,7 @@ private RubyModule buildModuleFromDescriptor(ThreadContext context) {
 
     RubyModule enumModule = RubyModule.newModule(runtime);
     boolean defaultValueRequiredButNotFound =
-        descriptor.getFile().getSyntax() == FileDescriptor.Syntax.PROTO3;
+        LegacyFileDescriptor.getSyntax(descriptor.getFile()) == LegacyFileDescriptor.Syntax.PROTO3;
     for (EnumValueDescriptor value : descriptor.getValues()) {
       String name = fixEnumConstantName(value.getName());
       // Make sure it's a valid constant name before trying to create it

ruby/src/main/java/com/google/protobuf/jruby/RubyFieldDescriptor.java

@@ -33,7 +33,7 @@
 package com.google.protobuf.jruby;
 
 import com.google.protobuf.Descriptors.FieldDescriptor;
-import com.google.protobuf.Descriptors.FileDescriptor;
+import com.google.protobuf.LegacyDescriptorsUtil.LegacyFileDescriptor;
 import org.jruby.*;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
@@ -234,7 +234,8 @@ public IRubyObject setValue(ThreadContext context, IRubyObject message, IRubyObj
   protected void setDescriptor(
       ThreadContext context, FieldDescriptor descriptor, RubyDescriptorPool pool) {
     if (descriptor.isRequired()
-        && descriptor.getFile().getSyntax() == FileDescriptor.Syntax.PROTO3) {
+        && LegacyFileDescriptor.getSyntax(descriptor.getFile())
+            == LegacyFileDescriptor.Syntax.PROTO3) {
       throw Utils.createTypeError(
           context,
           descriptor.getName()

ruby/src/main/java/com/google/protobuf/jruby/RubyFileDescriptor.java

@@ -33,8 +33,9 @@
 package com.google.protobuf.jruby;
 
 import com.google.protobuf.Descriptors.FileDescriptor;
-import com.google.protobuf.Descriptors.FileDescriptor.Syntax.*;
 import com.google.protobuf.Descriptors.GenericDescriptor;
+import com.google.protobuf.LegacyDescriptorsUtil.LegacyFileDescriptor;
+import com.google.protobuf.LegacyDescriptorsUtil.LegacyFileDescriptor.Syntax.*;
 import org.jruby.*;
 import org.jruby.anno.JRubyClass;
 import org.jruby.anno.JRubyMethod;
@@ -95,7 +96,7 @@ public IRubyObject getName(ThreadContext context) {
    */
   @JRubyMethod(name = "syntax")
   public IRubyObject getSyntax(ThreadContext context) {
-    switch (fileDescriptor.getSyntax()) {
+    switch (LegacyFileDescriptor.getSyntax(fileDescriptor)) {
       case PROTO2:
         return context.runtime.newSymbol("proto2");
       case PROTO3:

ruby/src/main/java/com/google/protobuf/jruby/RubyMessage.java

@@ -38,10 +38,10 @@
 import com.google.protobuf.Descriptors.EnumDescriptor;
 import com.google.protobuf.Descriptors.EnumValueDescriptor;
 import com.google.protobuf.Descriptors.FieldDescriptor;
-import com.google.protobuf.Descriptors.FileDescriptor;
 import com.google.protobuf.Descriptors.OneofDescriptor;
 import com.google.protobuf.DynamicMessage;
 import com.google.protobuf.InvalidProtocolBufferException;
+import com.google.protobuf.LegacyDescriptorsUtil.LegacyFileDescriptor;
 import com.google.protobuf.Message;
 import com.google.protobuf.UnknownFieldSet;
 import com.google.protobuf.util.JsonFormat;
@@ -73,7 +73,8 @@ public RubyMessage(Ruby runtime, RubyClass klazz, Descriptor descriptor) {
     this.builder = DynamicMessage.newBuilder(descriptor);
     this.fields = new HashMap<FieldDescriptor, IRubyObject>();
     this.oneofCases = new HashMap<OneofDescriptor, FieldDescriptor>();
-    this.proto3 = descriptor.getFile().getSyntax() == FileDescriptor.Syntax.PROTO3;
+    this.proto3 =
+        LegacyFileDescriptor.getSyntax(descriptor.getFile()) == LegacyFileDescriptor.Syntax.PROTO3;
   }
 
   /*