Fix NullPointerException in getSchemaType(Schema)

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -1166,11 +1166,13 @@ public String getSchemaType(Schema schema) {
         // TODO better logic to handle compose schema
         if (schema instanceof ComposedSchema) { // composed schema
             ComposedSchema cs = (ComposedSchema) schema;
-            for (Schema s : cs.getAllOf()) {
-                if (s != null) {
-                    // using the first schema defined in allOf
-                    schema = s;
-                    break;
+            if(cs.getAllOf() != null) {
+                for (Schema s : cs.getAllOf()) {
+                    if (s != null) {
+                        // using the first schema defined in allOf
+                        schema = s;
+                        break;
+                    }
                 }
             }
         }

modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java

@@ -202,4 +202,16 @@ public void testEnsureNoDuplicateProduces() {
         Assert.assertEquals(co.produces.size(), 1);
         Assert.assertEquals(co.produces.get(0).get("mediaType"), "application/json");
     }
+
+    @Test
+    public void testGetSchemaTypeWithComposedSchemaWithOneOf() {
+        final OpenAPI openAPI = new OpenAPIParser().readLocation("src/test/resources/3_0/composed-oneof.yaml", null, new ParseOptions()).getOpenAPI();
+        final DefaultCodegen codegen = new DefaultCodegen();
+
+        Operation operation = openAPI.getPaths().get("/state").getPost();
+        Schema schema = ModelUtils.getSchemaFromRequestBody(operation.getRequestBody());
+        String type = codegen.getSchemaType(schema);
+
+        Assert.assertNotNull(type);
+    }
 }

modules/openapi-generator/src/test/resources/3_0/composed-oneof.yaml

@@ -0,0 +1,61 @@
+openapi: 3.0.1
+info:
+  title: oneOf test
+  version: '1.0'
+servers:
+  - url: 'http://localhost:8000/'
+paths:
+  /state:
+    get:
+      operationId: getState
+      responses:
+        '200':
+          description: OK
+          content:
+            application/json:
+              schema:
+                oneOf:
+                  - $ref: '#/components/schemas/ObjA'
+                  - $ref: '#/components/schemas/ObjB'
+                discriminator:
+                  propertyName: realtype
+                  mapping:
+                    a-type: '#/components/schemas/ObjA'
+                    b-type: '#/components/schemas/ObjB'
+    post:
+      operationId: createState
+      requestBody:
+        content:
+            application/json:
+              schema:
+                oneOf:
+                  - $ref: '#/components/schemas/ObjA'
+                  - $ref: '#/components/schemas/ObjB'
+                discriminator:
+                  propertyName: realtype
+                  mapping:
+                    a-type: '#/components/schemas/ObjA'
+                    b-type: '#/components/schemas/ObjB'
+        required: true
+      responses:
+        '201':
+          description: OK
+components:
+  schemas:
+    ObjA:
+      type: object
+      properties:
+        realtype:
+          type: string
+        message:
+          type: string
+    ObjB:
+      type: object
+      properties:
+        realtype:
+          type: string
+        description:
+          type: string
+        code:
+          type: integer
+          format: int32