Fix model generation of array with items unique = true (#18104)

* Fix optional empty collection as default

* Fix test

* Fix test

* Fix default value collection handling

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

@@ -1036,6 +1036,7 @@ public class OpenAPINormalizer {
                 as.setMaxItems(schema.getMaxItems());
                 as.setExtensions(schema.getExtensions());
                 as.setXml(schema.getXml());
+                as.setUniqueItems(schema.getUniqueItems());
                 if (schema.getItems() != null) {
                     // `items` is also a json schema
                     if (StringUtils.isNotEmpty(schema.getItems().get$ref())) {

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

@@ -1103,13 +1103,13 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
      */
     public String toArrayDefaultValue(CodegenProperty cp, Schema schema) {
         if (schema.getDefault() != null) { // has default value
-            if (cp.isArray && !cp.getUniqueItems()) { // array
+            if (cp.isArray) {
                 List<String> _values = new ArrayList<>();
 
                 if (schema.getDefault() instanceof ArrayNode) { // array of default values
                     ArrayNode _default = (ArrayNode) schema.getDefault();
                     if (_default.isEmpty()) { // e.g. default: []
-                        return "new ArrayList<>()";
+                        return getDefaultCollectionType(schema);
                     }
 
                     List<String> final_values = _values;
@@ -1155,14 +1155,12 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
                         defaultValue = StringUtils.join(_values, ", ");
                     }
                 } else {
-                    return "new ArrayList<>()";
+                    return getDefaultCollectionType(schema);
                 }
 
-                return String.format(Locale.ROOT, "new ArrayList<>(Arrays.asList(%s))", defaultValue);
+                return getDefaultCollectionType(schema, defaultValue);
-            } else if (cp.isArray && cp.getUniqueItems()) { // set
+            }
-                // TODO
+            if (cp.isMap) { // map
-                return null;
-            } else if (cp.isMap) { // map
                 // TODO
                 return null;
             } else {
@@ -1181,18 +1179,10 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
                 // nullable or containerDefaultToNull set to true
                 if (cp.isNullable || containerDefaultToNull) {
                     return null;
-                } else {
-                    if (ModelUtils.isSet(schema)) {
-                        return String.format(Locale.ROOT, "new %s<>()",
-                                instantiationTypes().getOrDefault("set", "LinkedHashSet"));
-                    } else {
-                        return String.format(Locale.ROOT, "new %s<>()",
-                                instantiationTypes().getOrDefault("array", "ArrayList"));
                 }
+                return getDefaultCollectionType(schema);
             }
-            } else { // has default value
             return toArrayDefaultValue(cp, schema);
-            }
         } else if (ModelUtils.isMapSchema(schema) && !(ModelUtils.isComposedSchema(schema))) {
             if (schema.getProperties() != null && schema.getProperties().size() > 0) {
                 // object is complex object with free-form additional properties
@@ -1202,7 +1192,8 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
                 return null;
             }
 
-            if (cp.isNullable || containerDefaultToNull) { // nullable or containerDefaultToNull set to true
+            // nullable or containerDefaultToNull set to true
+            if (cp.isNullable || containerDefaultToNull) {
                 return null;
             }
 
@@ -1290,6 +1281,24 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
         return super.toDefaultValue(schema);
     }
 
+    private String getDefaultCollectionType(Schema schema) {
+        return getDefaultCollectionType(schema, null);
+    }
+
+    private String getDefaultCollectionType(Schema schema, String defaultValues) {
+        String arrayFormat = "new %s<>(Arrays.asList(%s))";
+        if(defaultValues == null || defaultValues.isEmpty()){
+            defaultValues = "";
+            arrayFormat = "new %s<>()";
+        }
+
+        if (ModelUtils.isSet(schema)) {
+            return String.format(Locale.ROOT, arrayFormat,
+                    instantiationTypes().getOrDefault("set", "LinkedHashSet"),defaultValues);
+        }
+        return String.format(Locale.ROOT, arrayFormat, instantiationTypes().getOrDefault("array", "ArrayList"),defaultValues);
+    }
+
     @Override
     public String toDefaultParameterValue(final Schema<?> schema) {
         Object defaultValue = schema.get$ref() != null ? ModelUtils.getReferencedSchema(openAPI, schema).getDefault() : schema.getDefault();

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

@@ -161,6 +161,20 @@ public class JavaFileAssert extends AbstractAssert<JavaFileAssert, CompilationUn
         return this;
     }
 
+    public JavaFileAssert fileDoesNotContains(final String... lines) {
+        final String actualBody = actual.getTokenRange()
+                .orElseThrow(() -> new IllegalStateException("Empty file"))
+                .toString();
+        Assertions.assertThat(actualBody)
+                .withFailMessage(
+                        "File should not contains lines\n====\n%s\n====\nbut actually was\n====\n%s\n====",
+                        Arrays.stream(lines).collect(Collectors.joining(System.lineSeparator())), actualBody
+                )
+                .doesNotContain(lines);
+
+        return this;
+    }
+
     public TypeAnnotationAssert assertTypeAnnotations() {
         return new TypeAnnotationAssert(this, actual.getType(0).getAnnotations());
     }

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

@@ -4548,4 +4548,46 @@ public class SpringCodegenTest {
                 .fileContains("private List<String> photoUrls = new ArrayList<>();");
 
     }
+
+    @Test
+    public void testCollectionTypesWithDefaults_issue_18102() throws IOException {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        output.deleteOnExit();
+
+        OpenAPI openAPI = new OpenAPIParser()
+                .readLocation("src/test/resources/3_1/java/issue_18102.yaml", null, new ParseOptions()).getOpenAPI();
+        SpringCodegen codegen = new SpringCodegen();
+        codegen.setLibrary(SPRING_CLOUD_LIBRARY);
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(CodegenConstants.MODEL_PACKAGE, "xyz.model");
+        codegen.additionalProperties().put(CodegenConstants.API_NAME_SUFFIX, "Controller");
+        codegen.additionalProperties().put(CodegenConstants.API_PACKAGE, "xyz.controller");
+        codegen.additionalProperties().put(CodegenConstants.MODEL_NAME_SUFFIX, "Dto");
+        codegen.setContainerDefaultToNull(true);
+
+
+        ClientOptInput input = new ClientOptInput()
+                .openAPI(openAPI)
+                .config(codegen);
+
+        DefaultGenerator generator = new DefaultGenerator();
+        Map<String, File> files = generator.opts(input).generate().stream()
+                .collect(Collectors.toMap(File::getName, Function.identity()));
+
+        JavaFileAssert.assertThat(files.get("PetDto.java"))
+                .fileContains("private List<@Valid TagDto> tags")
+                .fileContains("private List<@Valid TagDto> tagsDefaultList = new ArrayList<>()")
+                .fileContains("private Set<@Valid TagDto> tagsUnique")
+                .fileContains("private Set<@Valid TagDto> tagsDefaultSet = new LinkedHashSet<>();")
+                .fileContains("private List<String> stringList")
+                .fileContains("private List<String> stringDefaultList = new ArrayList<>(Arrays.asList(\"A\", \"B\"));")
+                .fileContains("private List<String> stringEmptyDefaultList = new ArrayList<>();")
+                .fileContains("Set<String> stringSet")
+                .fileContains("private Set<String> stringDefaultSet = new LinkedHashSet<>(Arrays.asList(\"A\", \"B\"));")
+                .fileContains("private Set<String> stringEmptyDefaultSet = new LinkedHashSet<>();")
+                .fileDoesNotContains("private List<@Valid TagDto> tags = new ArrayList<>()")
+                .fileDoesNotContains("private Set<@Valid TagDto> tagsUnique = new LinkedHashSet<>()")
+                .fileDoesNotContains("private List<String> stringList = new ArrayList<>()")
+                .fileDoesNotContains("private Set<String> stringSet = new LinkedHashSet<>()");
+    }
 }

modules/openapi-generator/src/test/resources/3_1/java/issue_18102.yaml

@@ -0,0 +1,112 @@
+openapi: 3.1.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: >-
+    This is a sample server Petstore server. For this sample, you can use the api key
+    `special-key` to test the authorization filters.
+  version: 1.0.0
+  title: OpenAPI Petstore
+  license:
+    name: Apache-2.0
+    url: 'https://www.apache.org/licenses/LICENSE-2.0.html'
+paths:
+  '/pet/{petId}':
+    get:
+      tags:
+        - pet
+      summary: Find pet by ID
+      description: Returns a single pet
+      operationId: getPetById
+      parameters:
+        - name: petId
+          in: path
+          description: ID of pet to return
+          required: true
+          schema:
+            type: integer
+            format: int64
+      responses:
+        '200':
+          description: successful operation
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Pet'
+        '400':
+          description: Invalid ID supplied
+        '404':
+          description: Pet not found
+components:
+  schemas:
+    Tag:
+      title: Pet Tag
+      description: A tag for a pet
+      type: object
+      properties:
+        id:
+          type: integer
+          format: int64
+        name:
+          type: string
+    Pet:
+      title: a Pet
+      description: A pet for sale in the pet store
+      type: object
+      properties:
+        tags:
+          type: array
+          items:
+            $ref: '#/components/schemas/Tag'
+        tagsDefaultList:
+          type: array
+          default: []
+          items:
+            $ref: '#/components/schemas/Tag'
+        tagsUnique:
+          type: array
+          uniqueItems: true
+          items:
+            $ref: '#/components/schemas/Tag'
+        tagsDefaultSet:
+          type: array
+          default: [ ]
+          uniqueItems: true
+          items:
+            $ref: '#/components/schemas/Tag'
+        stringList:
+          type: array
+          items:
+            type: string
+        stringDefaultList:
+          type: array
+          default:
+            - A
+            - B
+          items:
+            type: string
+        stringEmptyDefaultList:
+          type: array
+          default: []
+          items:
+            type: string
+        stringSet:
+          type: array
+          uniqueItems: true
+          items:
+            type: string
+        stringDefaultSet:
+          type: array
+          uniqueItems: true
+          default:
+            - A
+            - B
+          items:
+            type: string
+        stringEmptyDefaultSet:
+          type: array
+          uniqueItems: true
+          default: []
+          items:
+            type: string
+