[BUG][Java][Spring][SpringBoot] optional array with 'minItems' set generates to uninitialized list

Author: kingofdisasterr

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

@@ -1326,8 +1326,8 @@ public String toDefaultValue(CodegenProperty cp, Schema schema) {
                 // if default to empty container option is set, respect the default values provided in the spec
                 return toArrayDefaultValue(cp, schema);
             } else if (schema.getDefault() == null) {
-                // nullable or containerDefaultToNull set to true
-                if (cp.isNullable || containerDefaultToNull) {
+                // nullable or containerDefaultToNull set to true or an optional array with minItems > 0
+                if (cp.isNullable || containerDefaultToNull || (cp.minItems != null && cp.minItems > 0 && !cp.getHasRequired())) {
                     return null;
                 }
                 return getDefaultCollectionType(schema);

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

@@ -1590,7 +1590,6 @@ public void shouldGenerateDefaultValueForEnumRequestParameter() throws IOExcepti
         assertFileContains(Paths.get(outputPath + "/src/main/java/org/openapitools/api/GetApi.java"),
                 "@RequestParam(value = \"testParameter1\", required = false, defaultValue = \"BAR\")",
                 "@RequestParam(value = \"TestParameter2\", required = false, defaultValue = \"BAR\")");
-
     }
 
     /**
@@ -5075,7 +5074,36 @@ public void optionalListShouldBeEmpty() throws IOException {
         JavaFileAssert.assertThat(files.get("PetDto.java"))
                 .fileContains("private List<@Valid TagDto> tags = new ArrayList<>();")
                 .fileContains("private List<String> photoUrls = new ArrayList<>();");
+    }
+
+    @Test
+    public void testOptionalListWithMinItems1ShouldBeNull_issue_22784() throws IOException {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        output.deleteOnExit();
+
+        OpenAPI openAPI = new OpenAPIParser()
+                .readLocation("src/test/resources/3_1/issue_22784.yaml", null, new ParseOptions()).getOpenAPI();
+        SpringCodegen codegen = new SpringCodegen();
+        codegen.setOutputDir(output.getAbsolutePath());
+        codegen.additionalProperties().put(INTERFACE_ONLY, "true");
+        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");
+
+        ClientOptInput input = new ClientOptInput()
+                .openAPI(openAPI)
+                .config(codegen);
+
+        DefaultGenerator generator = new DefaultGenerator();
+        generator.setGenerateMetadata(false); // skip metadata and ↓ only generate models
+        generator.setGeneratorPropertyDefault(CodegenConstants.MODELS, "true");
+
+        Map<String, File> files = generator.opts(input).generate().stream()
+                .collect(Collectors.toMap(File::getName, Function.identity()));
 
+        JavaFileAssert.assertThat(files.get("FooBarRequestDto.java"))
+                .fileContains("private @Nullable List<@Valid BarDto> barList;");
     }
 
     @Test

modules/openapi-generator/src/test/resources/3_1/issue_22784.yaml

@@ -0,0 +1,45 @@
+openapi: 3.1.1
+info:
+  title: Optional Array with minItems 1 OpenAPI Example
+  version: 1.0.0
+paths:
+  /foo-bar:
+    put:
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/FooBarRequest'
+      responses:
+        204:
+          description: success
+
+components:
+  schemas:
+    FooBarRequest:
+      type: object
+      properties:
+        foo:
+          properties:
+            name:
+              type: string
+          required:
+            - name
+        barList:
+          description: |
+            This array is optional. If provided, it must contain between 1 and 3 items
+          type: array
+          items:
+            $ref: '#/components/schemas/Bar'
+          minItems: 1
+          maxItems: 3
+      required:
+        - foo
+    Bar:
+      type: object
+      properties:
+        someProperty:
+          type: string
+      required:
+        - someProperty