Hide deprecation behind flag

core/dbt/contracts/graph/semantic_manifest.py

@@ -59,17 +59,18 @@ def validate(self) -> bool:
 
         semantic_manifest = self._get_pydantic_semantic_manifest()
 
-        metrics_using_old_params: Set[str] = set()
-        for metric in semantic_manifest.metrics or []:
-            for field in ("window", "grain_to_date"):
-                type_params_field_value = getattr(metric.type_params, field)
-                # Warn that the old type_params structure has been deprecated.
-                if type_params_field_value:
-                    metrics_using_old_params.add(metric.name)
-        if metrics_using_old_params:
-            deprecations.warn(
-                "mf-cumulative-type-params-deprecation",
-            )
+        if get_flags().allow_legacy_mf_cumulative_type_params is False:
+            metrics_using_old_params: Set[str] = set()
+            for metric in semantic_manifest.metrics or []:
+                for field in ("window", "grain_to_date"):
+                    type_params_field_value = getattr(metric.type_params, field)
+                    # Warn that the old type_params structure has been deprecated.
+                    if type_params_field_value:
+                        metrics_using_old_params.add(metric.name)
+            if metrics_using_old_params:
+                deprecations.warn(
+                    "mf-cumulative-type-params-deprecation",
+                )
 
         new_time_spines = semantic_manifest.project_configuration.time_spines
         old_time_spines = semantic_manifest.project_configuration.time_spine_table_configurations