Restore the 3-argument internalBuildGeneratedFileFrom.

This is to restore gencode compatibility down to 3.0.0 on the 4.x line.

PiperOrigin-RevId: 816326810

Author: protobuf-github-bot

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

@@ -495,6 +495,45 @@ private static FileDescriptor[] findDescriptors(
       return descriptors.toArray(new FileDescriptor[0]);
     }
 
+    /**
+     * This method is for backward compatibility with generated code which passed an
+     * InternalDescriptorAssigner.
+     *
+     * @deprecated Any gencode which is using this method is far out of support and should be
+     *     regenerated with a newer version of the protobuf compiler.
+     */
+    @Deprecated
+    public static void internalBuildGeneratedFileFrom(
+        final String[] descriptorDataParts,
+        final FileDescriptor[] dependencies,
+        final InternalDescriptorAssigner descriptorAssigner) {
+      final byte[] descriptorBytes = latin1Cat(descriptorDataParts);
+
+      FileDescriptorProto proto;
+      try {
+        proto = FileDescriptorProto.parseFrom(descriptorBytes);
+      } catch (InvalidProtocolBufferException e) {
+        throw new IllegalArgumentException(
+            "Failed to parse protocol buffer descriptor for generated code.", e);
+      }
+
+      final FileDescriptor result;
+      try {
+        // When building descriptors for generated code, we allow unknown
+        // dependencies by default.
+        result = buildFrom(proto, dependencies, true);
+      } catch (DescriptorValidationException e) {
+        throw new IllegalArgumentException(
+            "Invalid embedded descriptor for \"" + proto.getName() + "\".", e);
+      }
+
+      final ExtensionRegistry registry = descriptorAssigner.assignDescriptors(result);
+
+      if (registry != null) {
+        throw new RuntimeException("assignDescriptors must return null");
+      }
+    }
+
     /**
      * This method is to be called by generated code only. It is equivalent to {@code buildFrom}
      * except that the {@code FileDescriptorProto} is encoded in protocol buffer wire format.