Fix TypedTabledEntity build

modules/loaders-common/src/main/scala/com/snowplowanalytics/snowplow/loaders/transform/TypedTabledEntity.scala

@@ -58,8 +58,11 @@ object TypedTabledEntity {
     subVersions: Set[SchemaSubVersion],
     schemas: NonEmptyList[SelfDescribingSchema[Schema]]
   ): Option[TypedTabledEntity] =
-    schemas
-      .traverse(sds => fieldFromSchema(tabledEntity, sds.schema).map((_, sds)))
+    schemas.toList
+      .flatMap { sds =>
+        fieldFromSchema(tabledEntity, sds.schema).map((_, sds))
+      }
+      .toNel
       .map { nel =>
         val (rootField, rootSchema) = nel.head
         val tte                     = TypedTabledEntity(tabledEntity, rootField, Set(keyToSubVersion(rootSchema.self.schemaKey)), Nil)

modules/loaders-common/src/test/resources/iglu-client-embedded/schemas/myvendor/test_empty_prop/jsonschema/1-0-0

@@ -0,0 +1,12 @@
+{
+    "$schema": "http://iglucentral.com/schemas/com.snowplowanalytics.self-desc/schema/jsonschema/1-0-0#",
+    "self": {
+        "vendor": "myvendor",
+        "name": "test_empty_prop",
+        "format": "jsonschema",
+        "version": "1-0-0"
+    },
+    "properties": {},
+    "additionalProperties": false,
+    "type": "object"
+}

modules/loaders-common/src/test/resources/iglu-client-embedded/schemas/myvendor/test_empty_prop/jsonschema/1-0-1

@@ -0,0 +1,14 @@
+{
+    "$schema": "http://iglucentral.com/schemas/com.snowplowanalytics.self-desc/schema/jsonschema/1-0-0#",
+    "self": {
+        "vendor": "myvendor",
+        "name": "test_empty_prop",
+        "format": "jsonschema",
+        "version": "1-0-1"
+    },
+    "properties": {
+      "myString": {"type": "string"}
+    },
+    "additionalProperties": false,
+    "type": "object"
+}

modules/loaders-common/src/test/scala/com.snowplowanalytics.snowplow.loaders/transform/NonAtomicFieldsSpec.scala

@@ -29,6 +29,7 @@ class NonAtomicFieldsSpec extends Specification with CatsEffect {
       return nothing for the Iglu Central ad_break_end_event schema $ue4
       return a JSON field for the Iglu Central anything-a schema $ue5
       return a field prefixed with underscore if field starts with a digit $ueDigit
+      return a merged schema if the batch has a schema with empty properties and additionalProperties=false $emptyProp
 
     when resolving for known schemas in contexts should
       return an un-merged schema if the batch uses the first schema in a series $c1
@@ -229,6 +230,37 @@ class NonAtomicFieldsSpec extends Specification with CatsEffect {
     }
   }
 
+  def emptyProp = {
+    val tabledEntity = TabledEntity(TabledEntity.UnstructEvent, "myvendor", "test_empty_prop", 1)
+
+    val input = Map(
+      tabledEntity -> Set((0, 1), (0, 0))
+    )
+
+    val expected = {
+      val expectedStruct = Type.Struct(
+        NonEmptyVector.of(
+          Field("my_string", Type.String, Nullable).copy(accessors = Set("myString"))
+        )
+      )
+
+      val expectedField = Field("unstruct_event_myvendor_test_empty_prop_1", expectedStruct, Nullable, Set.empty)
+
+      TypedTabledEntity(
+        tabledEntity,
+        expectedField,
+        Set((0, 1)),
+        Nil
+      )
+    }
+
+    NonAtomicFields.resolveTypes(embeddedResolver, input, List.empty).map { case NonAtomicFields.Result(fields, failures) =>
+      (failures must beEmpty) and
+        (fields must haveSize(1)) and
+        (fields.head must beEqualTo(expected))
+    }
+  }
+
   def c1 = {
 
     val tabledEntity = TabledEntity(TabledEntity.Context, "myvendor", "myschema", 7)