fix: ensure that @Nullable does not incorrectly affect object schemas

modules/swagger-core/src/main/java/io/swagger/v3/core/jackson/ModelResolver.java

@@ -124,6 +124,7 @@ public class ModelResolver extends AbstractModelConverter implements ModelConver
     public static boolean composedModelPropertiesAsSibling = System.getProperty(SET_PROPERTY_OF_COMPOSED_MODEL_AS_SIBLING) != null;
 
     private static final int SCHEMA_COMPONENT_PREFIX = "#/components/schemas/".length();
+    private static final String OBJECT_TYPE = "object";
 
     private static final Predicate<Annotation> ANNOTATIONS_THAT_SHOULD_BE_STRIPPED_FOR_CONTAINER_ITEMS = annotation ->
             annotation.annotationType().getName().startsWith("io.swagger") ||
@@ -179,19 +180,9 @@ public Schema resolve(AnnotatedType annotatedType, ModelConverterContext context
         }
 
         final Annotation resolvedSchemaOrArrayAnnotation = AnnotationsUtils.mergeSchemaAnnotations(annotatedType.getCtxAnnotations(), type);
-        final io.swagger.v3.oas.annotations.media.Schema resolvedSchemaAnnotation =
-                resolvedSchemaOrArrayAnnotation == null ?
-                        null :
-                        resolvedSchemaOrArrayAnnotation instanceof io.swagger.v3.oas.annotations.media.ArraySchema ?
-                                ((io.swagger.v3.oas.annotations.media.ArraySchema) resolvedSchemaOrArrayAnnotation).schema() :
-                                (io.swagger.v3.oas.annotations.media.Schema) resolvedSchemaOrArrayAnnotation;
-
-        final io.swagger.v3.oas.annotations.media.ArraySchema resolvedArrayAnnotation =
-                resolvedSchemaOrArrayAnnotation == null ?
-                        null :
-                        resolvedSchemaOrArrayAnnotation instanceof io.swagger.v3.oas.annotations.media.ArraySchema ?
-                                (io.swagger.v3.oas.annotations.media.ArraySchema) resolvedSchemaOrArrayAnnotation :
-                                null;
+        final io.swagger.v3.oas.annotations.media.Schema resolvedSchemaAnnotation = getSchemaAnnotation(resolvedSchemaOrArrayAnnotation);
+
+        final io.swagger.v3.oas.annotations.media.ArraySchema resolvedArrayAnnotation = getArraySchemaAnnotation(resolvedSchemaOrArrayAnnotation);
 
         final BeanDescription beanDesc;
         {
@@ -744,12 +735,7 @@ public Schema resolve(AnnotatedType annotatedType, ModelConverterContext context
                     propName = propSchemaName;
                 }
                 Annotation propSchemaOrArray = AnnotationsUtils.mergeSchemaAnnotations(annotations, propType);
-                final io.swagger.v3.oas.annotations.media.Schema propResolvedSchemaAnnotation =
-                        propSchemaOrArray == null ?
-                                null :
-                                propSchemaOrArray instanceof io.swagger.v3.oas.annotations.media.ArraySchema ?
-                                        ((io.swagger.v3.oas.annotations.media.ArraySchema) propSchemaOrArray).arraySchema() :
-                                        (io.swagger.v3.oas.annotations.media.Schema) propSchemaOrArray;
+                final io.swagger.v3.oas.annotations.media.Schema propResolvedSchemaAnnotation = getSchemaAnnotationForArray(propSchemaOrArray);
 
                 io.swagger.v3.oas.annotations.media.Schema.AccessMode accessMode = resolveAccessMode(propDef, type, propResolvedSchemaAnnotation);
                 io.swagger.v3.oas.annotations.media.Schema.RequiredMode requiredMode = resolveRequiredMode(propResolvedSchemaAnnotation, propType);
@@ -1123,11 +1109,7 @@ public Schema resolve(AnnotatedType annotatedType, ModelConverterContext context
         }
         // check if it has "object" related keywords
         if (isInferredObjectSchema(model) && model.get$ref() == null) {
-            if (openapi31 && model.getTypes() == null) {
-                model.addType("object");
-            } else if (!openapi31 && model.getType() == null) {
-                model.type("object");
-            }
+            setSchemaTypeForObjectSchema(model, resolvedSchemaAnnotation);
         }
         Schema.SchemaResolution resolvedSchemaResolution = AnnotationsUtils.resolveSchemaResolution(this.schemaResolution, resolvedSchemaAnnotation);
 
@@ -1165,6 +1147,24 @@ public Schema resolve(AnnotatedType annotatedType, ModelConverterContext context
         return model;
     }
 
+    private void setSchemaTypeForObjectSchema(Schema model, io.swagger.v3.oas.annotations.media.Schema schemaAnnotation) {
+        if (openapi31) {
+            if (model.getTypes() == null) {
+                model.addType(OBJECT_TYPE);
+            }
+            if (!isNullableSchema(model, schemaAnnotation)) {
+                model.setTypes(new LinkedHashSet<>(Collections.singletonList(OBJECT_TYPE)));
+            }
+        } else {
+            if (model.getType() == null) {
+                model.type(OBJECT_TYPE);
+            }
+            if (!isNullableSchema(model, schemaAnnotation)) {
+                model.setNullable(null);
+            }
+        }
+    }
+
     private Annotation[] addGenericTypeArgumentAnnotationsForOptionalField(BeanPropertyDefinition propDef, Annotation[] annotations) {
 
         boolean isNotOptionalType = Optional.ofNullable(propDef)
@@ -3040,12 +3040,7 @@ protected void resolveSchemaMembers(Schema schema, AnnotatedType annotatedType,
         }
 
         final Annotation resolvedSchemaOrArrayAnnotation = AnnotationsUtils.mergeSchemaAnnotations(annotatedType.getCtxAnnotations(), type);
-        final io.swagger.v3.oas.annotations.media.Schema schemaAnnotation =
-                resolvedSchemaOrArrayAnnotation == null ?
-                        null :
-                        resolvedSchemaOrArrayAnnotation instanceof io.swagger.v3.oas.annotations.media.ArraySchema ?
-                                ((io.swagger.v3.oas.annotations.media.ArraySchema) resolvedSchemaOrArrayAnnotation).schema() :
-                                (io.swagger.v3.oas.annotations.media.Schema) resolvedSchemaOrArrayAnnotation;
+        final io.swagger.v3.oas.annotations.media.Schema schemaAnnotation = getSchemaAnnotation(resolvedSchemaOrArrayAnnotation);
 
         final BeanDescription beanDesc = _mapper.getSerializationConfig().introspect(type);
         Annotated a = beanDesc.getClassInfo();
@@ -3489,6 +3484,25 @@ public void setConfiguration(Configuration configuration) {
         }
     }
 
+    /**
+     * Currently {@code null} is not a valid type for any {@code object} other than {@code AdditionalProperties}.
+     * This since the resolver currently does not produce proper nullable ref:s
+     * @param schema The schema that should be classified
+     * @param schemaAnnotation The schema annotation
+     * @return Whether the schema is considered valid for having the {@code null} type
+     */
+    private boolean isNullableSchema(Schema schema, io.swagger.v3.oas.annotations.media.Schema schemaAnnotation) {
+        if (openapi31) {
+            return isObjectSchema(schema) && schema.getAdditionalProperties() != null;
+        } else {
+            // If the schema annotation has explicitly set nullable to true, then keep that setting
+            if (schemaAnnotation != null && schemaAnnotation.nullable()) {
+                return true;
+            }
+            return isObjectSchema(schema) && schema.getAdditionalProperties() != null;
+        }
+    }
+
     protected boolean isObjectSchema(Schema schema) {
         return SchemaTypeUtils.isObjectSchema(schema);
     }
@@ -3564,6 +3578,36 @@ private Optional<Schema> resolveArraySchemaWithCycleGuard(
         return reResolvedProperty;
     }
 
+    private io.swagger.v3.oas.annotations.media.Schema getSchemaAnnotationForArray(Annotation annotation) {
+        if (annotation == null) {
+            return null;
+        } else {
+            return annotation instanceof io.swagger.v3.oas.annotations.media.ArraySchema ?
+                    ((io.swagger.v3.oas.annotations.media.ArraySchema) annotation).arraySchema() :
+                    (io.swagger.v3.oas.annotations.media.Schema) annotation;
+        }
+    }
+
+    private io.swagger.v3.oas.annotations.media.Schema getSchemaAnnotation(Annotation annotation) {
+        if (annotation == null) {
+            return null;
+        } else {
+            return annotation instanceof io.swagger.v3.oas.annotations.media.ArraySchema ?
+                    ((io.swagger.v3.oas.annotations.media.ArraySchema) annotation).schema() :
+                    (io.swagger.v3.oas.annotations.media.Schema) annotation;
+        }
+    }
+
+    private io.swagger.v3.oas.annotations.media.ArraySchema getArraySchemaAnnotation(Annotation annotation) {
+        if (annotation == null) {
+            return null;
+        } else {
+            return annotation instanceof io.swagger.v3.oas.annotations.media.ArraySchema ?
+                    (io.swagger.v3.oas.annotations.media.ArraySchema) annotation :
+                    null;
+        }
+    }
+
     /**
      * Checks if the given JavaType represents a java.util.stream.Stream
      */

modules/swagger-core/src/test/java/io/swagger/v3/core/issues/Issue5115Test.java

@@ -0,0 +1,238 @@
+package io.swagger.v3.core.issues;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.swagger.v3.core.converter.ModelConverters;
+import io.swagger.v3.core.converter.ResolvedSchema;
+import io.swagger.v3.core.util.Json;
+import io.swagger.v3.core.util.Json31;
+import io.swagger.v3.core.util.ResourceUtils;
+import io.swagger.v3.oas.annotations.media.Schema;
+import org.testng.annotations.Test;
+
+import javax.annotation.Nullable;
+import java.io.IOException;
+
+import static org.testng.Assert.assertEquals;
+
+/**
+ * Reproduces GitHub Issue #5115
+ * Issue using Nullable annotation on Model-fields
+ *
+ * <p>Tests that @Nullable annotation does not affect an object in an invalid manner. Any nullability that is configured
+ * with a schema annotation (nullable = true for OAS30 and null in types for OAS31) is retained.
+ *
+ * <p>Note: This test uses javax.annotation.Nullable which is automatically transformed to
+ * jakarta.annotation.Nullable in the swagger-core-jakarta module via the Eclipse Transformer.
+ */
+public class Issue5115Test {
+
+    @Test
+    public void testObjectDoesNotGetInvalidNullableSchemaOAS31() throws IOException {
+        ResolvedSchema schema = ModelConverters.getInstance(true)
+                .readAllAsResolvedSchema(ModelWithObject.class);
+
+        String expectedJson = ResourceUtils.loadClassResource(getClass(), "specFiles/NullableObjectFieldsOAS31.json");
+        String actualJson = Json31.pretty(schema);
+        ObjectMapper mapper = new ObjectMapper();
+        JsonNode expectedNode = mapper.readTree(expectedJson);
+        JsonNode actualNode = mapper.readTree(actualJson);
+        assertEquals(actualNode, expectedNode);
+    }
+
+    @Test
+    public void testObjectDoesNotGetInvalidNullableSchemaOAS30() throws IOException {
+        ResolvedSchema schema = ModelConverters.getInstance()
+                .readAllAsResolvedSchema(ModelWithObject.class);
+
+        String expectedJson = ResourceUtils.loadClassResource(getClass(), "specFiles/NullableObjectFieldsOAS30.json");
+        String actualJson = Json.pretty(schema);
+        ObjectMapper mapper = new ObjectMapper();
+        JsonNode expectedNode = mapper.readTree(expectedJson);
+        JsonNode actualNode = mapper.readTree(actualJson);
+        assertEquals(actualNode, expectedNode);
+    }
+
+    @Test
+    public void testObjectKeepsInvalidNullableSchemaIfSetInSchemaAnnotationOAS31() throws IOException {
+        ResolvedSchema schema = ModelConverters.getInstance(true)
+                .readAllAsResolvedSchema(ModelWithObjectThatHasNullableInSchemaAnnotationOAS31.class);
+
+        String expectedJson = ResourceUtils.loadClassResource(getClass(), "specFiles/NullableObjectFieldsSchemaAnnotationOAS31.json");
+        String actualJson = Json31.pretty(schema);
+        ObjectMapper mapper = new ObjectMapper();
+        JsonNode expectedNode = mapper.readTree(expectedJson);
+        JsonNode actualNode = mapper.readTree(actualJson);
+        assertEquals(actualNode, expectedNode);
+    }
+
+    @Test
+    public void testObjectKeepsInvalidNullableSchemaIfSetInSchemaAnnotationOAS30() throws IOException {
+        ResolvedSchema schema = ModelConverters.getInstance()
+                .readAllAsResolvedSchema(ModelWithObjectThatHasNullableInSchemaAnnotationOAS30.class);
+
+        String expectedJson = ResourceUtils.loadClassResource(getClass(), "specFiles/NullableObjectFieldsSchemaAnnotationOAS30.json");
+        String actualJson = Json.pretty(schema);
+        ObjectMapper mapper = new ObjectMapper();
+        JsonNode expectedNode = mapper.readTree(expectedJson);
+        JsonNode actualNode = mapper.readTree(actualJson);
+        assertEquals(actualNode, expectedNode);
+    }
+
+    public static class ModelWithObject {
+
+        @Nullable
+        private Model nullableModel;
+
+        private Model model;
+
+        @Nullable
+        public Model getNullableModel() {
+            return nullableModel;
+        }
+
+        public void setNullableModel(@Nullable Model model) {
+            this.nullableModel = model;
+        }
+
+        public Model getModel() {
+            return model;
+        }
+
+        public void setModel(Model model) {
+            this.model = model;
+        }
+    }
+
+    public static class ModelWithObjectThatHasNullableInSchemaAnnotationOAS30 {
+
+        // This nullable is lost since the fields are read top to bottom and model does not define nullable
+        @Schema(nullable = true)
+        private NestedModel nullableModel;
+
+        private NestedModel model;
+
+        @Schema(nullable = true)
+        private NestedModel2 nullableModel2;
+
+        public NestedModel getNullableModel() {
+            return nullableModel;
+        }
+
+        public void setNullableModel(NestedModel model) {
+            this.nullableModel = model;
+        }
+
+        public NestedModel getModel() {
+            return model;
+        }
+
+        public void setModel(NestedModel model) {
+            this.model = model;
+        }
+
+        public NestedModel2 getNullableModel2() {
+            return nullableModel2;
+        }
+
+        public void setNullableModel2(NestedModel2 nullableModel2) {
+            this.nullableModel2 = nullableModel2;
+        }
+    }
+
+    public static class ModelWithObjectThatHasNullableInSchemaAnnotationOAS31 {
+
+        @Schema(types = {"object", "null"})
+        private Model nullableModel;
+
+        private Model model;
+
+        public Model getNullableModel() {
+            return nullableModel;
+        }
+
+        public void setNullableModel(Model model) {
+            this.nullableModel = model;
+        }
+
+        public Model getModel() {
+            return model;
+        }
+
+        public void setModel(Model model) {
+            this.model = model;
+        }
+    }
+
+    public static class Model {
+
+        private NestedModel nestedModel;
+
+        @Nullable
+        private NestedModel nullableNestedModel;
+
+        @Nullable
+        private NestedModel2 nullableNestedModel2;
+
+        private NestedModel2 nestedModel2;
+
+        public NestedModel getNestedModel() {
+            return nestedModel;
+        }
+
+        public void setNestedModel(NestedModel nestedModel) {
+            this.nestedModel = nestedModel;
+        }
+
+        @Nullable
+        public NestedModel getNullableNestedModel() {
+            return nullableNestedModel;
+        }
+
+        public void setNullableNestedModel(@Nullable NestedModel nullableNestedModel) {
+            this.nullableNestedModel = nullableNestedModel;
+        }
+
+        @Nullable
+        public NestedModel2 getNullableNestedModel2() {
+            return nullableNestedModel2;
+        }
+
+        public void setNullableNestedModel2(@Nullable NestedModel2 nullableNestedModel2) {
+            this.nullableNestedModel2 = nullableNestedModel2;
+        }
+
+        public NestedModel2 getNestedModel2() {
+            return nestedModel2;
+        }
+
+        public void setNestedModel2(NestedModel2 nestedModel2) {
+            this.nestedModel2 = nestedModel2;
+        }
+    }
+
+    public static class NestedModel {
+        private String field;
+
+        public String getField() {
+            return field;
+        }
+
+        public void setField(String field) {
+            this.field = field;
+        }
+    }
+
+    public static class NestedModel2 {
+        private String field2;
+
+        public String getField2() {
+            return field2;
+        }
+
+        public void setField2(String field2) {
+            this.field2 = field2;
+        }
+    }
+
+}