httpclient: #426 Fix support for 204 no response body for HttpClient reading content

http-client/src/main/java/io/avaje/http/client/BodyAdapter.java

@@ -23,7 +23,6 @@ public interface BodyAdapter {
    * @param type The type of the bean this writer is for
    */
   default <T> BodyWriter<T> beanWriter(Type type) {
-
     throw new UnsupportedOperationException("java.lang.reflect.Type is not supported for this adapter");
   }
 

http-client/src/main/java/io/avaje/http/client/BodyContent.java

@@ -56,4 +56,9 @@ static BodyContent asJson(byte[] content) {
    * Return the content as UTF8 string.
    */
   String contentAsUtf8();
+
+  /**
+   * Return true if the content is empty.
+   */
+  boolean isEmpty();
 }

http-client/src/main/java/io/avaje/http/client/DBodyContent.java

@@ -36,6 +36,11 @@ public byte[] content() {
     return content;
   }
 
+  @Override
+  public boolean isEmpty() {
+    return content.length == 0;
+  }
+
   @Override
   public String contentAsUtf8() {
     return new String(content, StandardCharsets.UTF_8);

http-client/src/main/java/io/avaje/http/client/DBodyContentS.java

@@ -25,6 +25,11 @@ public byte[] content() {
     return content.getBytes(StandardCharsets.UTF_8);
   }
 
+  @Override
+  public boolean isEmpty() {
+    return content == null || content.isEmpty();
+  }
+
   @Override
   public String contentAsUtf8() {
     return content;

http-client/src/main/java/io/avaje/http/client/DHttpClientContext.java

@@ -5,6 +5,7 @@
 import java.net.http.HttpRequest;
 import java.net.http.HttpResponse;
 import java.time.Duration;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
@@ -274,20 +275,32 @@ <T> BodyReader<T> beanReader(Type type) {
   }
 
   <T> T readBean(Class<T> type, BodyContent content) {
+    if (content.isEmpty()) {
+      return null;
+    }
     return bodyAdapter.beanReader(type).read(content);
   }
 
   <T> List<T> readList(Class<T> type, BodyContent content) {
+    if (content.isEmpty()) {
+      return Collections.emptyList();
+    }
     return bodyAdapter.listReader(type).read(content);
   }
 
   @SuppressWarnings("unchecked")
   <T> T readBean(Type type, BodyContent content) {
+    if (content.isEmpty()) {
+      return null;
+    }
     return (T) bodyAdapter.beanReader(type).read(content);
   }
 
   @SuppressWarnings("unchecked")
   <T> List<T> readList(Type type, BodyContent content) {
+    if (content.isEmpty()) {
+      return Collections.emptyList();
+    }
     return (List<T>) bodyAdapter.listReader(type).read(content);
   }
 

tests/test-nima-jsonb/src/main/java/org/example/TestController.java

@@ -1,10 +1,7 @@
 package org.example;
 
 import java.io.InputStream;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 
 import io.avaje.http.api.BodyString;
 import io.avaje.http.api.Controller;
@@ -155,4 +152,14 @@ String pattern(String patty) {
   String patternPlus(String plus) {
     return plus.toString();
   }
+
+  @Get("/maybe/{maybe}")
+  Person maybePerson(boolean maybe) {
+    return maybe ? new Person(9, "hi") : null;
+  }
+
+  @Get("/maybeList/{maybe}")
+  List<Person> maybePersonList(boolean maybe) {
+    return maybe ? List.of(new Person(9, "hi")) : null; // Collections.emptyList();
+  }
 }

tests/test-nima-jsonb/src/test/java/io/avaje/http/generator/NimaProcessorTest.java

@@ -45,7 +45,7 @@ void runAnnotationProcessor() throws Exception {
 
     final var task =
         compiler.getTask(
-            new PrintWriter(System.out), null, null, List.of("--release=20", "-AdisableDirectWrites=true"), null, files);
+            new PrintWriter(System.out), null, null, List.of("--release=21", "-AdisableDirectWrites=true"), null, files);
     task.setProcessors(List.of(new HelidonProcessor()));
 
     assertThat(task.call()).isTrue();
@@ -61,7 +61,7 @@ void runAnnotationProcessorWithJsonB() throws Exception {
 
     final var task =
         compiler.getTask(
-            new PrintWriter(System.out), null, null, List.of("--release=19"), null, files);
+            new PrintWriter(System.out), null, null, List.of("--release=21"), null, files);
     task.setProcessors(List.of(new HelidonProcessor()));
 
     assertThat(task.call()).isTrue();

tests/test-nima-jsonb/src/test/java/org/example/TestControllerTest.java

@@ -3,6 +3,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 import java.net.http.HttpResponse;
+import java.util.List;
 
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.Test;
@@ -121,4 +122,38 @@ void ithrowIllegalStateException() {
 
     assertThat(res.statusCode()).isEqualTo(503);
   }
+
+  @Test
+  void testNoBodyResponse() {
+    HttpResponse<Person> res = client.request()
+      .path("test/maybe/true")
+      .GET().as(Person.class);
+
+    assertThat(res.statusCode()).isEqualTo(200);
+    assertThat(res.body().name()).isEqualTo("hi");
+
+    HttpResponse<Person> resNoBody = client.request()
+      .path("test/maybe/false")
+      .GET().as(Person.class);
+
+    assertThat(resNoBody.statusCode()).isEqualTo(204);
+    assertThat(resNoBody.body()).isNull();
+  }
+
+  @Test
+  void testNoBodyListResponse() {
+    HttpResponse<List<Person>> res = client.request()
+      .path("test/maybeList/true")
+      .GET().asList(Person.class);
+
+    assertThat(res.statusCode()).isEqualTo(200);
+    assertThat(res.body().getFirst().name()).isEqualTo("hi");
+
+    HttpResponse<List<Person>> resNoBody = client.request()
+      .path("test/maybeList/false")
+      .GET().asList(Person.class);
+
+    assertThat(resNoBody.statusCode()).isEqualTo(204);
+    assertThat(resNoBody.body()).isEmpty();
+  }
 }