feat(codec): Add Jackson 3 support module (feign-jackson3)

jackson3/README.md

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+Jackson 3 Codec
+===================
+
+This module adds support for encoding and decoding JSON via Jackson 3.
+
+**Note:** Jackson 3 requires Java 17 or higher.
+
+Add `Jackson3Encoder` and/or `Jackson3Decoder` to your `Feign.Builder` like so:
+
+```java
+GitHub github = Feign.builder()
+                     .encoder(new Jackson3Encoder())
+                     .decoder(new Jackson3Decoder())
+                     .target(GitHub.class, "https://api.github.com");
+```
+
+If you want to customize the `JsonMapper` that is used, provide it to the `Jackson3Encoder` and `Jackson3Decoder`:
+
+```java
+JsonMapper mapper = JsonMapper.builder()
+        .changeDefaultPropertyInclusion(incl -> incl.withValueInclusion(JsonInclude.Include.NON_NULL))
+        .enable(SerializationFeature.INDENT_OUTPUT)
+        .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
+        .build();
+
+GitHub github = Feign.builder()
+                     .encoder(new Jackson3Encoder(mapper))
+                     .decoder(new Jackson3Decoder(mapper))
+                     .target(GitHub.class, "https://api.github.com");
+```
+
+## Migration from Jackson 2 to Jackson 3
+
+The main differences are:
+
+- Package changes: `com.fasterxml.jackson` → `tools.jackson` (except for `com.fasterxml.jackson.annotation`)
+- GroupId changes: `com.fasterxml.jackson.core` → `tools.jackson.core`
+- `ObjectMapper` is immutable and must be configured via `JsonMapper.builder()`
+- Java 17 minimum requirement

jackson3/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright © 2012 The Feign Authors (feign@commonhaus.dev)
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>io.github.openfeign</groupId>
+    <artifactId>feign-parent</artifactId>
+    <version>13.7-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>feign-jackson3</artifactId>
+  <name>Feign Jackson 3</name>
+  <description>Feign Jackson 3</description>
+
+  <properties>
+    <!-- Jackson 3 requires Java 17 -->
+    <main.java.version>17</main.java.version>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>feign-core</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>tools.jackson.core</groupId>
+      <artifactId>jackson-databind</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>feign-core</artifactId>
+      <type>test-jar</type>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+</project>

jackson3/src/main/java/feign/jackson3/Jackson3Decoder.java

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+/*
+ * Copyright © 2012 The Feign Authors (feign@commonhaus.dev)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package feign.jackson3;
+
+import feign.Response;
+import feign.Util;
+import feign.codec.Decoder;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.Reader;
+import java.lang.reflect.Type;
+import java.util.Collections;
+import tools.jackson.core.JacksonException;
+import tools.jackson.databind.DeserializationFeature;
+import tools.jackson.databind.JacksonModule;
+import tools.jackson.databind.json.JsonMapper;
+
+public class Jackson3Decoder implements Decoder {
+
+  private final JsonMapper mapper;
+
+  public Jackson3Decoder() {
+    this(Collections.<JacksonModule>emptyList());
+  }
+
+  public Jackson3Decoder(Iterable<JacksonModule> modules) {
+    this(
+        JsonMapper.builder()
+            .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
+            .addModules(modules)
+            .build());
+  }
+
+  public Jackson3Decoder(JsonMapper mapper) {
+    this.mapper = mapper;
+  }
+
+  @Override
+  public Object decode(Response response, Type type) throws IOException {
+    if (response.status() == 404 || response.status() == 204) return Util.emptyValueOf(type);
+    if (response.body() == null) return null;
+    Reader reader = response.body().asReader(response.charset());
+    if (!reader.markSupported()) {
+      reader = new BufferedReader(reader, 1);
+    }
+    try {
+      // Read the first byte to see if we have any data
+      reader.mark(1);
+      if (reader.read() == -1) {
+        return null; // Eagerly returning null avoids "No content to map due to end-of-input"
+      }
+      reader.reset();
+      return mapper.readValue(reader, mapper.constructType(type));
+    } catch (JacksonException e) {
+      if (e.getCause() != null && e.getCause() instanceof IOException) {
+        throw IOException.class.cast(e.getCause());
+      }
+      throw e;
+    }
+  }
+}

jackson3/src/main/java/feign/jackson3/Jackson3Encoder.java

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+/*
+ * Copyright © 2012 The Feign Authors (feign@commonhaus.dev)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package feign.jackson3;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import feign.RequestTemplate;
+import feign.Util;
+import feign.codec.EncodeException;
+import feign.codec.Encoder;
+import java.lang.reflect.Type;
+import java.util.Collections;
+import tools.jackson.core.JacksonException;
+import tools.jackson.databind.JacksonModule;
+import tools.jackson.databind.JavaType;
+import tools.jackson.databind.SerializationFeature;
+import tools.jackson.databind.json.JsonMapper;
+
+public class Jackson3Encoder implements Encoder {
+
+  private final JsonMapper mapper;
+
+  public Jackson3Encoder() {
+    this(Collections.<JacksonModule>emptyList());
+  }
+
+  public Jackson3Encoder(Iterable<JacksonModule> modules) {
+    this(
+        JsonMapper.builder()
+            .changeDefaultPropertyInclusion(
+                incl -> incl.withValueInclusion(JsonInclude.Include.NON_NULL))
+            .enable(SerializationFeature.INDENT_OUTPUT)
+            .addModules(modules)
+            .build());
+  }
+
+  public Jackson3Encoder(JsonMapper mapper) {
+    this.mapper = mapper;
+  }
+
+  @Override
+  public void encode(Object object, Type bodyType, RequestTemplate template) {
+    try {
+      JavaType javaType = mapper.getTypeFactory().constructType(bodyType);
+      template.body(mapper.writerFor(javaType).writeValueAsBytes(object), Util.UTF_8);
+    } catch (JacksonException e) {
+      throw new EncodeException(e.getMessage(), e);
+    }
+  }
+}