fix(api): preserve null data in response envelopes

common-core/pom.xml

@@ -14,6 +14,7 @@
     <name>baiyue-common-core</name>
 
     <dependencies>
+        <dependency><groupId>com.fasterxml.jackson.core</groupId><artifactId>jackson-annotations</artifactId></dependency>
         <dependency><groupId>org.springframework</groupId><artifactId>spring-web</artifactId></dependency>
         <dependency>
             <groupId>com.baomidou</groupId>

common-core/src/main/java/com/baiyue/common/core/api/ApiResponse.java

@@ -1,5 +1,7 @@
 package com.baiyue.common.core.api;
 
+import com.fasterxml.jackson.annotation.JsonInclude;
+
 import java.time.Instant;
 
 /**
@@ -8,7 +10,7 @@ import java.time.Instant;
 public record ApiResponse<T>(
         String code,
         String message,
-        T data,
+        @JsonInclude(JsonInclude.Include.ALWAYS) T data,
         String requestId,
         String traceId,
         Instant timestamp) {

common-web/src/test/java/com/baiyue/common/web/ApiResponseSerializationTest.java

@@ -0,0 +1,43 @@
+package com.baiyue.common.web;
+
+import com.baiyue.common.core.api.ApiResponse;
+import com.baiyue.common.core.api.ResultCode;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.autoconfigure.AutoConfigurations;
+import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class ApiResponseSerializationTest {
+    @Test
+    void preservesEnvelopeDataUnderNonNullConfiguration() {
+        new ApplicationContextRunner()
+                .withConfiguration(AutoConfigurations.of(JacksonAutoConfiguration.class))
+                .withPropertyValues("spring.jackson.default-property-inclusion=non_null")
+                .run(context -> {
+                    ObjectMapper mapper = context.getBean(ObjectMapper.class);
+                    JsonNode success = mapper.readTree(mapper.writeValueAsString(ApiResponse.success(null)));
+                    assertThat(success.path("code").asText()).isEqualTo("200");
+                    assertThat(success.has("data")).isTrue();
+                    assertThat(success.get("data").isNull()).isTrue();
+                    assertThat(success.has("requestId")).isFalse();
+
+                    JsonNode failure = mapper.readTree(mapper.writeValueAsString(
+                            ApiResponse.failure(ResultCode.CONFLICT, "conflict", "request-1", "trace-1")));
+                    assertThat(failure.path("code").asText()).isEqualTo("A0409");
+                    assertThat(failure.has("data")).isTrue();
+                    assertThat(failure.get("data").isNull()).isTrue();
+                    assertThat(failure.path("requestId").asText()).isEqualTo("request-1");
+                    assertThat(failure.path("traceId").asText()).isEqualTo("trace-1");
+
+                    JsonNode populated = mapper.readTree(mapper.writeValueAsString(
+                            ApiResponse.success(Map.of("status", "SUBMITTED"))));
+                    assertThat(populated.path("data").path("status").asText()).isEqualTo("SUBMITTED");
+                });
+    }
+}