fix: Preserve x-* on permissive object and multi-assertion AllOfSchema wrapper

When a schema map has only x-* keys (no type, no combinators, no shape
keywords), the synthesized permissive ObjectSchema previously discarded
them. Likewise, when parseMap collapsed multiple assertions into a
wrapper AllOfSchema, the wrapper carried Map.of() instead of the
top-level extensions. Both call sites now pass extractExtensions(raw).

Author: thced

src/main/java/com/retailsvc/http/spec/schema/SchemaParser.java

@@ -61,9 +61,9 @@ private static Schema parseMap(Map<String, Object> raw) {
     }
 
     return switch (assertions.size()) {
-      case 0 -> permissiveObject();
+      case 0 -> permissiveObject(extractExtensions(raw));
       case 1 -> assertions.getFirst();
-      default -> new AllOfSchema(List.copyOf(assertions), Map.of());
+      default -> new AllOfSchema(List.copyOf(assertions), extractExtensions(raw));
     };
   }
 
@@ -115,9 +115,9 @@ private static boolean hasArrayShapeKeywords(Map<String, Object> raw) {
         || raw.containsKey("uniqueItems");
   }
 
-  private static Schema permissiveObject() {
+  private static Schema permissiveObject(Map<String, Object> extensions) {
     return new ObjectSchema(
-        Set.of(), Map.of(), List.of(), new AdditionalProperties.Allowed(), null, null, Map.of());
+        Set.of(), Map.of(), List.of(), new AdditionalProperties.Allowed(), null, null, extensions);
   }
 
   private static Set<TypeName> parseTypes(Map<String, Object> raw) {

src/test/java/com/retailsvc/http/spec/ExtensionsTest.java

@@ -170,4 +170,52 @@ void oneOfSchemaExtensionsExposeXKeys() {
     assertThat(spec.componentSchemas().get("Either").extensions())
         .containsEntry("x-discriminator-hint", "kind");
   }
+
+  @Test
+  void permissiveObjectPreservesXKeys() {
+    Map<String, Object> raw =
+        Map.of(
+            "openapi",
+            "3.1.0",
+            "info",
+            Map.of("title", "t", "version", "1"),
+            "servers",
+            List.of(Map.of("url", "https://example.com")),
+            "paths",
+            Map.of(),
+            "components",
+            Map.of("schemas", Map.of("FreeForm", Map.of("x-vendor", "acme"))));
+    Spec spec = Spec.from(raw);
+    assertThat(spec.componentSchemas().get("FreeForm").extensions())
+        .containsEntry("x-vendor", "acme");
+  }
+
+  @Test
+  void multiAssertionWrapperPreservesXKeys() {
+    Map<String, Object> raw =
+        Map.of(
+            "openapi",
+            "3.1.0",
+            "info",
+            Map.of("title", "t", "version", "1"),
+            "servers",
+            List.of(Map.of("url", "https://example.com")),
+            "paths",
+            Map.of(),
+            "components",
+            Map.of(
+                "schemas",
+                Map.of(
+                    "Composite",
+                    Map.of(
+                        "type",
+                        "object",
+                        "anyOf",
+                        List.of(Map.of("type", "object"), Map.of("type", "object")),
+                        "x-tag",
+                        "composite"))));
+    Spec spec = Spec.from(raw);
+    assertThat(spec.componentSchemas().get("Composite").extensions())
+        .containsEntry("x-tag", "composite");
+  }
 }