Update model builder to be backwards compatible with mobilenet_v2_fpn_sep_conv

PiperOrigin-RevId: 368024164

research/object_detection/builders/model_builder.py

@@ -170,6 +170,8 @@ if tf_version.is_tf2():
           center_net_mobilenet_v2_feature_extractor.mobilenet_v2,
       'mobilenet_v2_fpn':
           center_net_mobilenet_v2_fpn_feature_extractor.mobilenet_v2_fpn,
+      'mobilenet_v2_fpn_sep_conv':
+          center_net_mobilenet_v2_fpn_feature_extractor.mobilenet_v2_fpn,
   }
 
   FEATURE_EXTRACTOR_MAPS = [
@@ -1123,12 +1125,16 @@ def _build_center_net_feature_extractor(feature_extractor_config, is_training):
   if feature_extractor_config.type not in CENTER_NET_EXTRACTOR_FUNCTION_MAP:
     raise ValueError('\'{}\' is not a known CenterNet feature extractor type'
                      .format(feature_extractor_config.type))
+  # For backwards compatibility:
+  use_separable_conv = (
+      feature_extractor_config.use_separable_conv or
+      feature_extractor_config.type == 'mobilenet_v2_fpn_sep_conv')
   kwargs = {
       'channel_means': list(feature_extractor_config.channel_means),
       'channel_stds': list(feature_extractor_config.channel_stds),
       'bgr_ordering': feature_extractor_config.bgr_ordering,
       'depth_multiplier': feature_extractor_config.depth_multiplier,
-      'use_separable_conv': feature_extractor_config.use_separable_conv,
+      'use_separable_conv': use_separable_conv,
   }