Removing the Jackson leak in HttpHeaders, instead registering a separ…

…ate serializer directly with the JacksonAdapter. Tests that failed after functionality was removed from HttpHeaders now pass with the new HttpHeaderSerializer. (#4597)

sdk/core/azure-core/src/main/java/com/azure/core/http/HttpHeaders.java

@@ -3,12 +3,6 @@
 
 package com.azure.core.http;
 
-import com.fasterxml.jackson.core.JsonGenerator;
-import com.fasterxml.jackson.databind.JsonSerializable;
-import com.fasterxml.jackson.databind.SerializerProvider;
-import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
-
-import java.io.IOException;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Locale;
@@ -17,7 +11,7 @@
 /**
  * A collection of headers on an HTTP request or response.
  */
-public class HttpHeaders implements Iterable<HttpHeader>, JsonSerializable {
+public class HttpHeaders implements Iterable<HttpHeader> {
     private final Map<String, HttpHeader> headers = new HashMap<>();
 
     /**
@@ -128,14 +122,4 @@ public Map<String, String> toMap() {
     public Iterator<HttpHeader> iterator() {
         return headers.values().iterator();
     }
-
-    @Override
-    public void serialize(JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException {
-        jsonGenerator.writeObject(toMap());
-    }
-
-    @Override
-    public void serializeWithType(JsonGenerator jsonGenerator, SerializerProvider serializerProvider, TypeSerializer typeSerializer) throws IOException {
-        serialize(jsonGenerator, serializerProvider);
-    }
 }

sdk/core/azure-core/src/main/java/com/azure/core/implementation/serializer/jackson/HttpHeadersSerializer.java

@@ -0,0 +1,35 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package com.azure.core.implementation.serializer.jackson;
+
+import com.azure.core.http.HttpHeaders;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.SerializerProvider;
+import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
+import com.fasterxml.jackson.databind.module.SimpleModule;
+
+import java.io.IOException;
+
+/**
+ * Custom serializer for serializing {@code HttpHeaders} objects into Base64 strings.
+ */
+final class HttpHeadersSerializer extends JsonSerializer<HttpHeaders> {
+    /**
+     * Gets a module wrapping this serializer as an adapter for the Jackson
+     * ObjectMapper.
+     *
+     * @return a simple module to be plugged onto Jackson ObjectMapper.
+     */
+    public static SimpleModule getModule() {
+        SimpleModule module = new SimpleModule();
+        module.addSerializer(HttpHeaders.class, new HttpHeadersSerializer());
+        return module;
+    }
+
+    @Override
+    public void serialize(HttpHeaders value, JsonGenerator jgen, SerializerProvider provider) throws IOException {
+        jgen.writeObject(value.toMap());
+    }
+}

sdk/core/azure-core/src/main/java/com/azure/core/implementation/serializer/jackson/JacksonAdapter.java

@@ -170,7 +170,8 @@ private static <T extends ObjectMapper> T initializeObjectMapper(T mapper) {
                 .registerModule(Base64UrlSerializer.getModule())
                 .registerModule(DateTimeSerializer.getModule())
                 .registerModule(DateTimeRfc1123Serializer.getModule())
-                .registerModule(DurationSerializer.getModule());
+                .registerModule(DurationSerializer.getModule())
+                .registerModule(HttpHeadersSerializer.getModule());
         mapper.setVisibility(mapper.getSerializationConfig().getDefaultVisibilityChecker()
                 .withFieldVisibility(JsonAutoDetect.Visibility.ANY)
                 .withSetterVisibility(JsonAutoDetect.Visibility.NONE)