[core] consider polymorphism when computing unused schemas (#4335)

Fixed #4193

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

@@ -90,6 +90,7 @@ public class ModelUtils {
      * @return schemas a list of used schemas
      */
     public static List<String> getAllUsedSchemas(OpenAPI openAPI) {
+        Map<String, List<String>> childrenMap = getChildrenMap(openAPI);
         List<String> allUsedSchemas = new ArrayList<String>();
         visitOpenAPI(openAPI, (s, t) -> {
             if (s.get$ref() != null) {
@@ -97,6 +98,13 @@ public class ModelUtils {
                 if (!allUsedSchemas.contains(ref)) {
                     allUsedSchemas.add(ref);
                 }
+                if (childrenMap.containsKey(ref)) {
+                    for (String child : childrenMap.get(ref)) {
+                        if (!allUsedSchemas.contains(child)) {
+                            allUsedSchemas.add(child);
+                        }
+                    }
+                }
             }
         });
         return allUsedSchemas;
@@ -109,6 +117,7 @@ public class ModelUtils {
      * @return schemas a list of unused schemas
      */
     public static List<String> getUnusedSchemas(OpenAPI openAPI) {
+        Map<String, List<String>> childrenMap = getChildrenMap(openAPI);
         List<String> unusedSchemas = new ArrayList<String>();
 
         Map<String, Schema> schemas = getSchemas(openAPI);
@@ -116,7 +125,11 @@ public class ModelUtils {
 
         visitOpenAPI(openAPI, (s, t) -> {
             if (s.get$ref() != null) {
-                unusedSchemas.remove(getSimpleRef(s.get$ref()));
+                String ref = getSimpleRef(s.get$ref());
+                unusedSchemas.remove(ref);
+                if (childrenMap.containsKey(ref)) {
+                    unusedSchemas.removeAll(childrenMap.get(ref));
+                }
             }
         });
         return unusedSchemas;
@@ -859,6 +872,18 @@ public class ModelUtils {
         return null;
     }
 
+    public static Map<String, List<String>> getChildrenMap(OpenAPI openAPI) {
+        Map<String, Schema> allSchemas = getSchemas(openAPI);
+
+        Map<String, List<Entry<String, Schema>>> groupedByParent = allSchemas.entrySet().stream()
+            .filter(entry -> isComposedSchema(entry.getValue()))
+            .collect(Collectors.groupingBy(entry -> getParentName((ComposedSchema) entry.getValue(), allSchemas)));
+
+        return groupedByParent.entrySet().stream()
+                .collect(Collectors.toMap(entry -> entry.getKey(), entry -> entry.getValue().stream().map(e -> e.getKey()).collect(Collectors.toList())));
+    }
+
+
     /**
      * Get the interfaces from the schema (composed)
      *

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

@@ -37,7 +37,7 @@ public class ModelUtilsTest {
     public void testGetAllUsedSchemas() {
         final OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/unusedSchemas.yaml");
         List<String> allUsedSchemas = ModelUtils.getAllUsedSchemas(openAPI);
-        Assert.assertEquals(allUsedSchemas.size(), 38);
+        Assert.assertEquals(allUsedSchemas.size(), 41);
 
         Assert.assertTrue(allUsedSchemas.contains("SomeObjShared"), "contains 'SomeObjShared'");
         Assert.assertTrue(allUsedSchemas.contains("SomeObj1"), "contains 'UnusedObj1'");
@@ -77,21 +77,30 @@ public class ModelUtilsTest {
         Assert.assertTrue(allUsedSchemas.contains("SomeObj26"), "contains 'SomeObj26'");
         Assert.assertTrue(allUsedSchemas.contains("Param27"), "contains 'Param27'");
         Assert.assertTrue(allUsedSchemas.contains("Param28"), "contains 'Param28'");
+        Assert.assertTrue(allUsedSchemas.contains("Parent30"), "contains 'Parent30'");
+        Assert.assertTrue(allUsedSchemas.contains("AChild30"), "contains 'AChild30'");
+        Assert.assertTrue(allUsedSchemas.contains("BChild30"), "contains 'BChild30'");
     }
 
     @Test
     public void testGetUnusedSchemas() {
         final OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/unusedSchemas.yaml");
         List<String> unusedSchemas = ModelUtils.getUnusedSchemas(openAPI);
-        Assert.assertEquals(unusedSchemas.size(), 4);
+        Assert.assertEquals(unusedSchemas.size(), 7);
-        //UnusedObj is not used at all:
+        //UnusedObj1 is not used at all:
         Assert.assertTrue(unusedSchemas.contains("UnusedObj1"), "contains 'UnusedObj1'");
-        //SomeObjUnused is used in a request body that is not used.
+        //UnusedObj2 is used in a request body that is not used.
         Assert.assertTrue(unusedSchemas.contains("UnusedObj2"), "contains 'UnusedObj2'");
-        //SomeObjUnused is used in a response that is not used.
+        //UnusedObj3 is used in a response that is not used.
         Assert.assertTrue(unusedSchemas.contains("UnusedObj3"), "contains 'UnusedObj3'");
-        //SomeObjUnused is used in a parameter that is not used.
+        //UnusedObj4 is used in a parameter that is not used.
         Assert.assertTrue(unusedSchemas.contains("UnusedObj4"), "contains 'UnusedObj4'");
+        //Parent29 is not used at all (only unused children AChild29 and BChild29 are referencing him):
+        Assert.assertTrue(unusedSchemas.contains("Parent29"), "contains 'Parent29'");
+        //AChild29 is not used at all:
+        Assert.assertTrue(unusedSchemas.contains("AChild29"), "contains 'AChild29'");
+        //BChild29 is not used at all:
+        Assert.assertTrue(unusedSchemas.contains("BChild29"), "contains 'BChild29'");
     }
 
     @Test

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

@@ -352,6 +352,17 @@ paths:
       responses:
         '200':
           description: OK
+  /some/p30:
+    post:
+      operationId: op27
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/Parent30"
+      responses:
+        '200':
+          description: OK
 components:
   schemas:
     UnusedObj1:
@@ -641,6 +652,56 @@ components:
           type: string
         r2:
           type: string
+    Parent29:
+      type: object
+      required:
+      - childType
+      properties:
+        childType:
+          type: string
+      discriminator:
+        propertyName: childType
+    AChild29:
+      allOf:
+      - $ref: '#/components/schemas/Parent29'
+      - type: object
+        properties:
+          name:
+            type: string
+    BChild29:
+      allOf:
+      - $ref: '#/components/schemas/Parent29'
+      - type: object
+        properties:
+          firstName:
+            type: string
+          lastName:
+            type: string
+    Parent30:
+      type: object
+      required:
+      - childType
+      properties:
+        childType:
+          type: string
+      discriminator:
+        propertyName: childType
+    AChild30:
+      allOf:
+      - $ref: '#/components/schemas/Parent30'
+      - type: object
+        properties:
+          name:
+            type: string
+    BChild30:
+      allOf:
+      - $ref: '#/components/schemas/Parent30'
+      - type: object
+        properties:
+          firstName:
+            type: string
+          lastName:
+            type: string
     SomeObjShared:
       type: object
       properties: