feat: add support for default enum values in Jackson annotations (#2324)

Author: frankrenaerseveresst

src/generators/java/presets/JacksonPreset.ts

@@ -91,6 +91,17 @@ export const JAVA_JACKSON_PRESET: JavaPreset = {
     }
   },
   enum: {
+    // Fallback for unknown enum values has to be configured on the ObjectMapper
+    // objectMapper.configure(
+    //  DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE, true
+    // );
+    item({ content, model, item }) {
+      const defaultEnumValue = model.originalInput?.default;
+      if (item.originalInput === defaultEnumValue) {
+        return `@JsonEnumDefaultValue ${content}`;
+      }
+      return content;
+    },
     self({ renderer, content }) {
       renderer.dependencyManager.addDependency(JACKSON_ANNOTATION_DEPENDENCY);
       return content;

test/generators/java/presets/JacksonPreset.spec.ts

@@ -44,6 +44,23 @@ describe('JAVA_JACKSON_PRESET', () => {
     expect(models[0].dependencies).toEqual(expectedDependencies);
   });
 
+  test('should render Jackson annotations with default for enum', async () => {
+    const doc = {
+      $id: 'Status',
+      type: 'string',
+      description: 'Description for enum',
+      enum: ['on', 'off'],
+      default: 'off'
+    };
+
+    const expectedDependencies = ['import com.fasterxml.jackson.annotation.*;'];
+
+    const models = await generator.generate(doc);
+    expect(models).toHaveLength(1);
+    expect(models[0].result).toMatchSnapshot();
+    expect(models[0].dependencies).toEqual(expectedDependencies);
+  });
+
   test('should not render anything when isExtended is true', async () => {
     const extend = {
       $id: 'extend',

test/generators/java/presets/__snapshots__/JacksonPreset.spec.ts.snap

@@ -81,6 +81,38 @@ exports[`JAVA_JACKSON_PRESET should render Jackson annotations for enum 1`] = `
 }"
 `;
 
+exports[`JAVA_JACKSON_PRESET should render Jackson annotations with default for enum 1`] = `
+"public enum Status {
+  ON((String)\\"on\\"), @JsonEnumDefaultValue OFF((String)\\"off\\");
+
+  private final String value;
+
+  Status(String value) {
+    this.value = value;
+  }
+
+  @JsonValue
+  public String getValue() {
+    return value;
+  }
+
+  @JsonCreator
+  public static Status fromValue(String value) {
+    for (Status e : Status.values()) {
+      if (e.value.equals(value)) {
+        return e;
+      }
+    }
+    throw new IllegalArgumentException(\\"Unexpected value '\\" + value + \\"'\\");
+  }
+
+  @Override
+  public String toString() {
+    return String.valueOf(value);
+  }
+}"
+`;
+
 exports[`JAVA_JACKSON_PRESET union handle oneOf with AsyncAPI discriminator with Jackson 1`] = `
 Array [
   "@JsonTypeInfo(use=JsonTypeInfo.Id.NAME, include=JsonTypeInfo.As.EXISTING_PROPERTY, property=\\"vehicle_type\\", visible=true)