diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
index 8fd12a5faf1..e24ac519491 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
@@ -2563,8 +2563,9 @@ public class DefaultCodegen implements CodegenConfig {
         CodegenParameter bodyParam = null;
         RequestBody requestBody = operation.getRequestBody();
         if (requestBody != null) {
-            if (getContentType(requestBody).toLowerCase(Locale.ROOT).startsWith("application/x-www-form-urlencoded") ||
-                    getContentType(requestBody).toLowerCase(Locale.ROOT).startsWith("multipart/form-data")) {
+            if (getContentType(requestBody) != null &&
+                    (getContentType(requestBody).toLowerCase(Locale.ROOT).startsWith("application/x-www-form-urlencoded") ||
+                    getContentType(requestBody).toLowerCase(Locale.ROOT).startsWith("multipart/form-data"))) {
                 // process form parameters
                 formParams = fromRequestBodyToFormParameters(requestBody, imports);
                 for (CodegenParameter cp : formParams) {
@@ -4256,8 +4257,8 @@ public class DefaultCodegen implements CodegenConfig {
 
     protected String getContentType(RequestBody requestBody) {
         if (requestBody == null || requestBody.getContent() == null || requestBody.getContent().isEmpty()) {
-            LOGGER.warn("Cannot determine the content type. Default to UNKNOWN_CONTENT_TYPE.");
-            return "UNKNOWN_CONTENT_TYPE";
+            LOGGER.debug("Cannot determine the content type. Returning null.");
+            return null;
         }
         return new ArrayList<>(requestBody.getContent().keySet()).get(0);
     }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java
index 69931a20104..1226eaba9fe 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java
@@ -434,9 +434,9 @@ public class DefaultGenerator extends AbstractGenerator implements Generator {
                 if (unusedModels.contains(name)) {
                     if (Boolean.FALSE.equals(skipFormModel)) {
                         // if skipFormModel sets to true, still generate the model and log the result
-                        LOGGER.info("Model " + name + " (marked as unused due to form parameters) is generated due to skipFormModel=false (default)");
+                        LOGGER.info("Model " + name + " (marked as unused due to form parameters) is generated due to the system property skipFormModel=false (default)");
                     } else {
-                        LOGGER.info("Model " + name + " not generated since it's marked as unused (due to form parameters) and skipFormModel set to true");
+                        LOGGER.info("Model " + name + " not generated since it's marked as unused (due to form parameters) and skipFormModel (system property) set to true");
                         continue;
                     }
                 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientCodegenTest.java
index 1ce890c2a91..b0a5bf59604 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientCodegenTest.java
@@ -521,6 +521,47 @@ public class RubyClientCodegenTest {
         Assert.assertEquals(cp1.name, "person_required");
     }
 
+    @Test(description = "test allOf composition")
+    public void allOfCompositionTest() {
+        final OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/allOf_composition.yaml");
+        final RubyClientCodegen codegen = new RubyClientCodegen();
+        codegen.setModuleName("OnlinePetstore");
+
+        final Schema schema = openAPI.getComponents().getSchemas().get("SuperMan");
+        codegen.setOpenAPI(openAPI);
+        CodegenModel superMan = codegen.fromModel("SuperMan", schema);
+        Assert.assertNotNull(superMan);
+
+        // to test all properties
+        Assert.assertEquals(superMan.getVars().size(), 6);
+
+        CodegenProperty cp0 = superMan.getVars().get(0);
+        Assert.assertEquals(cp0.name, "id");
+        Assert.assertTrue(cp0.required);
+
+        CodegenProperty cp1 = superMan.getVars().get(1);
+        Assert.assertEquals(cp1.name, "name");
+        Assert.assertFalse(cp1.required);
+
+        CodegenProperty cp2 = superMan.getVars().get(2);
+        Assert.assertEquals(cp2.name, "reward");
+        Assert.assertFalse(cp2.required);
+
+        CodegenProperty cp3 = superMan.getVars().get(3);
+        Assert.assertEquals(cp3.name, "origin");
+        Assert.assertTrue(cp3.required);
+
+        CodegenProperty cp4 = superMan.getVars().get(4);
+        Assert.assertEquals(cp4.name, "category");
+        Assert.assertFalse(cp4.required);
+
+        CodegenProperty cp5 = superMan.getVars().get(5);
+        Assert.assertEquals(cp5.name, "level");
+        Assert.assertTrue(cp5.required);
+
+    }
+
+
     @Test(description = "test example string imported from x-example parameterr (OAS2)")
     public void exampleStringFromExampleParameterOAS2Test() {
         final OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/2_0/petstore-nullable.yaml");
diff --git a/modules/openapi-generator/src/test/resources/3_0/allOf_composition.yaml b/modules/openapi-generator/src/test/resources/3_0/allOf_composition.yaml
new file mode 100644
index 00000000000..93ddc36c604
--- /dev/null
+++ b/modules/openapi-generator/src/test/resources/3_0/allOf_composition.yaml
@@ -0,0 +1,63 @@
+openapi: 3.0.1
+info:
+  version: 1.0.0
+  title: Example
+  license:
+    name: MIT
+servers:
+  - url: http://api.example.xyz/v1
+paths:
+  /person/display/{personId}:
+    get:
+      parameters:
+        - name: personId
+          in: path
+          required: true
+          description: The id of the person to retrieve
+          schema:
+            type: string
+      operationId: list
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/SuperMan"
+components:
+  schemas:
+    SuperMan:
+      allOf:
+      - $ref: '#/components/schemas/Human'
+      - $ref: '#/components/schemas/Hero'
+      - type: object
+        required:
+          - level
+        properties:
+          category:
+            type: string
+          level:
+            type: integer 
+    Hero:
+      description: Hero
+      type: object
+      required:
+        - origin
+      properties:
+        reward:
+          type: integer
+          format: int64
+        origin:
+          type: string
+    Human:
+      description: Human
+      type: object
+      required:
+        - id
+      properties:
+        id:
+          type: integer
+          format: int64
+        name:
+          type: string
+          example: Tom