Don't validate partition keys on embedded entity types.

src/EFCore.Cosmos/Extensions/CosmosEntityTypeExtensions.cs

@@ -26,8 +26,10 @@ public static string GetCosmosContainer([NotNull] this IEntityType entityType) =
                   ?? GetCosmosDefaultContainer(entityType);
 
         private static string GetCosmosDefaultContainer(IEntityType entityType)
-            => entityType.Model.GetCosmosDefaultContainer()
-               ?? entityType.ShortName();
+            => entityType.IsOwned()
+               ? null
+               : entityType.Model.GetCosmosDefaultContainer()
+                  ?? entityType.ShortName();
 
         /// <summary>
         ///     Sets the name of the container to which the entity type is mapped.

src/EFCore.Cosmos/Internal/CosmosModelValidator.cs

@@ -57,6 +57,10 @@ protected virtual void ValidateSharedContainerCompatibility(
             foreach (var entityType in model.GetEntityTypes().Where(et => et.FindPrimaryKey() != null))
             {
                 var container = entityType.GetCosmosContainer();
+                if (container == null)
+                {
+                    continue;
+                }
 
                 if (!containers.TryGetValue(container, out var mappedTypes))
                 {

src/EFCore.Cosmos/Properties/CosmosStrings.resx

@@ -130,7 +130,7 @@
     <value>The entity type '{entityType}' is sharing the container '{container}' with other types, but does not have a discriminator value configured.</value>
   </data>
   <data name="NoPartitionKey" xml:space="preserve">
-    <value>The entity type '{entityType}' does not have a partition key set, but it is mapped to the collection '{collection}' shared by entity types with partition keys.</value>
+    <value>The entity type '{entityType}' does not have a partition key set, but it is mapped to the container '{container}' shared by entity types with partition keys.</value>
   </data>
   <data name="OrphanedNestedDocument" xml:space="preserve">
     <value>The entity of type '{entityType}' is mapped as a part of the document mapped to '{missingEntityType}', but there is no tracked entity of this type with the corresponding key value. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the key values.</value>

src/EFCore.Cosmos/Storage/Internal/CosmosDatabaseCreator.cs

@@ -53,9 +53,13 @@ public virtual bool EnsureCreated()
             var created = _cosmosClient.CreateDatabaseIfNotExists();
             foreach (var entityType in _model.GetEntityTypes())
             {
-                created |= _cosmosClient.CreateContainerIfNotExists(
-                    entityType.GetCosmosContainer(),
-                    GetCosmosPartitionKeyStoreName(entityType));
+                var containerName = entityType.GetCosmosContainer();
+                if (containerName != null)
+                {
+                    created |= _cosmosClient.CreateContainerIfNotExists(
+                        containerName,
+                        GetCosmosPartitionKeyStoreName(entityType));
+                }
             }
 
             if (created)

test/EFCore.Cosmos.Tests/Infrastructure/CosmosModelValidatorTest.cs

@@ -142,6 +142,13 @@ private class Order
             public int Id { get; set; }
             public string PartitionId { get; set; }
             public Customer Customer { get; set; }
+            public OrderDetails OrderDetails { get; set; }
+        }
+
+        [Owned]
+        private class OrderDetails
+        {
+            public string ShippingAddress { get; set; }
         }
     }
 }