Google.Protobuf.JsonFormatter.WriteStructFieldValue C# (CSharp) Method

        private void WriteStructFieldValue(TextWriter writer, IMessage message)
        {
            var specifiedField = message.Descriptor.Oneofs[0].Accessor.GetCaseFieldDescriptor(message);
            if (specifiedField == null)
            {
                throw new InvalidOperationException("Value message must contain a value for the oneof.");
            }

            object value = specifiedField.Accessor.GetValue(message);
            
            switch (specifiedField.FieldNumber)
            {
                case Value.BoolValueFieldNumber:
                case Value.StringValueFieldNumber:
                case Value.NumberValueFieldNumber:
                    WriteValue(writer, value);
                    return;
                case Value.StructValueFieldNumber:
                case Value.ListValueFieldNumber:
                    // Structs and ListValues are nested messages, and already well-known types.
                    var nestedMessage = (IMessage) specifiedField.Accessor.GetValue(message);
                    WriteWellKnownTypeValue(writer, nestedMessage.Descriptor, nestedMessage);
                    return;
                case Value.NullValueFieldNumber:
                    WriteNull(writer);
                    return;
                default:
                    throw new InvalidOperationException("Unexpected case in struct field: " + specifiedField.FieldNumber);
            }
        }