auto fix self-reference schemas

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

@@ -493,12 +493,64 @@ public class OpenAPINormalizer {
                     }
                 }
 
+                // auto fix self reference schema to avoid stack overflow
+                fixSelfReferenceSchema(schemaName, schema);
+
                 // normalize the schemas
                 schemas.put(schemaName, normalizeSchema(schema, new HashSet<>()));
             }
         }
     }
 
+    /**
+     * Auto fix a self referencing schema using any type to replace the self-referencing sub-item.
+     *
+     * @param name           Schema name
+     * @param schema         Schema
+     */
+    public void fixSelfReferenceSchema(String name, Schema schema) {
+        if (ModelUtils.isArraySchema(schema)) {
+            if (isSelfReference(name, schema.getItems())) {
+                LOGGER.error("Array schema {} has a sub-item referencing itself. Worked around the self-reference schema using any type instead.", name);
+                schema.setItems(new Schema<>());
+            }
+        }
+
+        if (ModelUtils.isOneOf(schema)) {
+            for (int i = 0; i < schema.getOneOf().size(); i++) {
+                if (isSelfReference(name, (Schema) schema.getOneOf().get(i))) {
+                    LOGGER.error("oneOf schema {} has a sub-item referencing itself. Worked around the self-reference schema by removing it.", name);
+                    schema.getOneOf().remove(i);
+                }
+            }
+        }
+
+        if (ModelUtils.isAnyOf(schema)) {
+            for (int i = 0; i < schema.getAnyOf().size(); i++) {
+                if (isSelfReference(name, (Schema) schema.getAnyOf().get(i))) {
+                    LOGGER.error("anyOf schema {} has a sub-item referencing itself. Worked around the self-reference schema by removing it.", name);
+                    schema.getAnyOf().remove(i);
+                }
+            }
+        }
+
+        if (schema.getAdditionalProperties() != null && schema.getAdditionalProperties() instanceof Schema) {
+            if (isSelfReference(name, (Schema) schema.getAdditionalProperties())) {
+                LOGGER.error("Schema {} (with additional properties) has a sub-item referencing itself. Worked around the self-reference schema using any type instead.", name);
+                schema.setAdditionalProperties(new Schema<>());
+            }
+        }
+
+    }
+
+    private boolean isSelfReference(String name, Schema subSchema) {
+        if (subSchema != null && name.equals(ModelUtils.getSimpleRef(subSchema.get$ref()))) {
+            return true;
+        } else {
+            return false;
+        }
+    }
+
     /**
      * Normalizes a schema
      *

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

@@ -1493,7 +1493,7 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
         MediaType mediaType = content.values().iterator().next();
         if (mediaType.getExample() != null) {
             if (isModel) {
-                LOGGER.warn("Ignoring complex example on request body");
+                once(LOGGER).warn("Ignoring complex example on request body");
             } else {
                 codegenParameter.example = mediaType.getExample().toString();
                 return;
@@ -1504,7 +1504,7 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
             Example example = mediaType.getExamples().values().iterator().next();
             if (example.getValue() != null) {
                 if (isModel) {
-                    LOGGER.warn("Ignoring complex example on request body");
+                    once(LOGGER).warn("Ignoring complex example on request body");
                 } else {
                     codegenParameter.example = example.getValue().toString();
                     return;

modules/openapi-generator/src/test/resources/3_1/java/petstore.yaml

@@ -1066,3 +1066,24 @@ components:
         - $ref: '#/components/schemas/SimpleModelWithArrayProperty'
     myObject:
       type: object
+    SelfReference:
+      type: array
+      items:
+        $ref: "#/components/schemas/SelfReference"
+    SelfReferenceOneOf:
+      oneOf:
+        - type: string
+        - type: boolean
+        - $ref: "#/components/schemas/SelfReferenceOneOf"
+    SelfReferenceAnyOf:
+      anyOf:
+        - type: string
+        - type: boolean
+        - $ref: "#/components/schemas/SelfReferenceAnyOf"
+    SelfReferenceAdditionalProperties:
+      type: object
+      additionalProperties:
+        $ref: "#/components/schemas/SelfReferenceAdditionalProperties"
+      properties:
+        dummy:
+          type: string 

samples/client/petstore/java/okhttp-gson-3.1/.openapi-generator/FILES

@@ -24,6 +24,9 @@ docs/Pet.md
 docs/PetApi.md
 docs/RefRefToPathLevelParameterOneofRefToOneofParameter.md
 docs/RefToRefParameterAnyofRefToAnyofParameter.md
+docs/SelfReferenceAdditionalProperties.md
+docs/SelfReferenceAnyOf.md
+docs/SelfReferenceOneOf.md
 docs/SimpleModelWithArrayProperty.md
 docs/StoreApi.md
 docs/StringOrInt.md
@@ -82,6 +85,9 @@ src/main/java/org/openapitools/client/model/Order.java
 src/main/java/org/openapitools/client/model/Pet.java
 src/main/java/org/openapitools/client/model/RefRefToPathLevelParameterOneofRefToOneofParameter.java
 src/main/java/org/openapitools/client/model/RefToRefParameterAnyofRefToAnyofParameter.java
+src/main/java/org/openapitools/client/model/SelfReferenceAdditionalProperties.java
+src/main/java/org/openapitools/client/model/SelfReferenceAnyOf.java
+src/main/java/org/openapitools/client/model/SelfReferenceOneOf.java
 src/main/java/org/openapitools/client/model/SimpleModelWithArrayProperty.java
 src/main/java/org/openapitools/client/model/StringOrInt.java
 src/main/java/org/openapitools/client/model/Tag.java

samples/client/petstore/java/okhttp-gson-3.1/README.md

@@ -166,6 +166,9 @@ Class | Method | HTTP request | Description
  - [Pet](docs/Pet.md)
  - [RefRefToPathLevelParameterOneofRefToOneofParameter](docs/RefRefToPathLevelParameterOneofRefToOneofParameter.md)
  - [RefToRefParameterAnyofRefToAnyofParameter](docs/RefToRefParameterAnyofRefToAnyofParameter.md)
+ - [SelfReferenceAdditionalProperties](docs/SelfReferenceAdditionalProperties.md)
+ - [SelfReferenceAnyOf](docs/SelfReferenceAnyOf.md)
+ - [SelfReferenceOneOf](docs/SelfReferenceOneOf.md)
  - [SimpleModelWithArrayProperty](docs/SimpleModelWithArrayProperty.md)
  - [StringOrInt](docs/StringOrInt.md)
  - [Tag](docs/Tag.md)

samples/client/petstore/java/okhttp-gson-3.1/api/openapi.yaml

@@ -1160,6 +1160,22 @@ components:
       - $ref: '#/components/schemas/SimpleModelWithArrayProperty'
     myObject:
       type: object
+    SelfReference:
+      items: {}
+      type: array
+    SelfReferenceOneOf:
+      oneOf:
+      - type: string
+      - type: boolean
+    SelfReferenceAnyOf:
+      anyOf:
+      - type: string
+      - type: boolean
+    SelfReferenceAdditionalProperties:
+      additionalProperties: {}
+      properties:
+        dummy:
+          type: string
     updatePetWithForm_request:
       properties:
         name:

samples/client/petstore/java/okhttp-gson-3.1/src/main/java/org/openapitools/client/JSON.java

@@ -137,6 +137,9 @@ public class JSON {
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Pet.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.RefRefToPathLevelParameterOneofRefToOneofParameter.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.RefToRefParameterAnyofRefToAnyofParameter.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.SelfReferenceAdditionalProperties.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.SelfReferenceAnyOf.CustomTypeAdapterFactory());
+        gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.SelfReferenceOneOf.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.SimpleModelWithArrayProperty.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.StringOrInt.CustomTypeAdapterFactory());
         gsonBuilder.registerTypeAdapterFactory(new org.openapitools.client.model.Tag.CustomTypeAdapterFactory());