Allow model server to reload a config if it doesn't change from the previous loading attempt.

PiperOrigin-RevId: 760460942

Author: lilao

tensorflow_serving/model_servers/server_core.cc

@@ -24,6 +24,7 @@ limitations under the License.
 
 #include "google/protobuf/any.pb.h"
 #include "google/protobuf/wrappers.pb.h"
+#include "google/protobuf/util/message_differencer.h"
 #include "tensorflow/core/lib/core/stringpiece.h"
 #include "tensorflow/core/lib/io/path.h"
 #include "tensorflow/core/lib/strings/strcat.h"
@@ -453,7 +454,8 @@ Status ServerCore::ReloadConfig(const ModelServerConfig& new_config) {
   const bool accept_transition =
       is_first_config ||
       (config_.config_case() == ModelServerConfig::kModelConfigList &&
-       new_config.config_case() == ModelServerConfig::kModelConfigList);
+       new_config.config_case() == ModelServerConfig::kModelConfigList) ||
+      protobuf::util::MessageDifferencer::Equals(config_, new_config);
   if (!accept_transition) {
     return errors::FailedPrecondition(
         "Cannot transition to requested config. It is only legal to transition "