diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java
index 47bf588ae89f..ba4815d90f99 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/ModelUtils.java
@@ -2661,8 +2661,18 @@ public static boolean isUnsupportedSchema(OpenAPI openAPI, Schema schema) {
         // dereference the schema
         schema = ModelUtils.getReferencedSchema(openAPI, schema);
 
-        if (schema.getTypes() == null && hasValidation(schema)) {
+        if (schema.getTypes() == null && schema.getType() == null && hasValidation(schema)
+                && (schema.getProperties() == null || schema.getProperties().isEmpty())) {
             // just validation without type
+            //
+            // A schema that carries properties is a model, even when it omits `type: object` --
+            // which is very common in 3.0 specs, e.g. `minProperties: 2` next to `properties: {...}`.
+            // Checking `getTypes() == null && hasValidation(schema)` alone classified those as
+            // unsupported, and as an allOf member their properties were then dropped from the
+            // composed model without any warning.
+            //
+            // getTypes() is only populated for 3.1, so getType() has to be checked as well for the
+            // 3.0 case to be recognised.
             return true;
         } else if (schema.getIf() != null && schema.getThen() != null) {
             // if, then in 3.1 spec
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java
index e9e0ad0d9563..e8493bb00ff4 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java
@@ -38,6 +38,41 @@ public class OpenAPINormalizerTest {
     private static final String X_PARENT = "x-parent";
     private static final String X_INTERNAL = "x-internal";
 
+    @Test
+    public void testAllOfMemberWithValidationAndPropertiesIsKept() {
+        // A schema carrying `properties` but omitting `type: object`, next to a validation keyword,
+        // is a model -- not "validation without a type". It used to be classified as unsupported and
+        // silently dropped from allOf, so every model inheriting it lost those properties.
+        OpenAPI openAPI = TestUtils.parseSpec(
+                "src/test/resources/3_0/allof-member-with-validation-and-properties.yaml");
+
+        Schema child = openAPI.getComponents().getSchemas().get("Child");
+        assertNotNull(child.getAllOf());
+        assertTrue(refsParent(child), "precondition: Child starts out referencing Parent");
+
+        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, new HashMap<>());
+        openAPINormalizer.normalize();
+
+        Schema normalizedChild = openAPI.getComponents().getSchemas().get("Child");
+        assertNotNull(normalizedChild.getAllOf(),
+                "the whole allOf was dropped, so Child lost the inherited properties");
+        assertTrue(refsParent(normalizedChild),
+                "the allOf member carrying alpha/beta was dropped, so Child lost those properties");
+    }
+
+    private static boolean refsParent(Schema schema) {
+        if (schema.getAllOf() == null) {
+            return false;
+        }
+        for (Object item : schema.getAllOf()) {
+            String ref = ((Schema) item).get$ref();
+            if (ref != null && ref.endsWith("/Parent")) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     @Test
     public void testOpenAPINormalizerOtherThanObjectWithProperties()
     {
diff --git a/modules/openapi-generator/src/test/resources/3_0/allof-member-with-validation-and-properties.yaml b/modules/openapi-generator/src/test/resources/3_0/allof-member-with-validation-and-properties.yaml
new file mode 100644
index 000000000000..0d34de1f7e7d
--- /dev/null
+++ b/modules/openapi-generator/src/test/resources/3_0/allof-member-with-validation-and-properties.yaml
@@ -0,0 +1,32 @@
+openapi: 3.0.3
+info:
+  title: allOf member with validation and properties
+  version: 1.0.0
+paths:
+  /child:
+    get:
+      operationId: getChild
+      responses:
+        "200":
+          description: ok
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/Child"
+components:
+  schemas:
+    # `properties` without an explicit `type: object`, next to a validation keyword.
+    # This is a model, not "validation without a type".
+    Parent:
+      minProperties: 2
+      properties:
+        alpha:
+          type: string
+        beta:
+          type: string
+    Child:
+      allOf:
+        - $ref: "#/components/schemas/Parent"
+      properties:
+        gamma:
+          type: string