From 589a0a91248dfe916079316397fb95310784620c Mon Sep 17 00:00:00 2001
From: Alexander Zadvinskiy <azadvinskiy@it-one.ru>
Date: Fri, 4 Mar 2022 17:59:04 +0300
Subject: [PATCH 1/2] Add ability use case insensitive headers for default
 Client

---
 core/src/main/java/feign/Client.java          |  9 +++++----
 .../java/feign/client/DefaultClientTest.java  | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/core/src/main/java/feign/Client.java b/core/src/main/java/feign/Client.java
index 38058eccd..b52d1cd30 100644
--- a/core/src/main/java/feign/Client.java
+++ b/core/src/main/java/feign/Client.java
@@ -20,6 +20,7 @@
 import static feign.Util.checkArgument;
 import static feign.Util.checkNotNull;
 import static feign.Util.isNotBlank;
+import static java.lang.String.CASE_INSENSITIVE_ORDER;
 import static java.lang.String.format;
 import feign.Request.Options;
 import java.io.IOException;
@@ -31,9 +32,9 @@
 import java.nio.charset.StandardCharsets;
 import java.util.Base64;
 import java.util.Collection;
-import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.TreeMap;
 import java.util.zip.DeflaterOutputStream;
 import java.util.zip.GZIPInputStream;
 import java.util.zip.GZIPOutputStream;
@@ -114,7 +115,7 @@ Response convertResponse(HttpURLConnection connection, Request request) throws I
             connection.getRequestMethod(), connection.getURL()));
       }
 
-      Map<String, Collection<String>> headers = new LinkedHashMap<>();
+      Map<String, Collection<String>> headers =  new TreeMap<>(CASE_INSENSITIVE_ORDER);
       for (Map.Entry<String, List<String>> field : connection.getHeaderFields().entrySet()) {
         // response message
         if (field.getKey() != null) {
@@ -130,9 +131,9 @@ Response convertResponse(HttpURLConnection connection, Request request) throws I
       if (status >= 400) {
         stream = connection.getErrorStream();
       } else {
-        if (this.isGzip(connection.getHeaderFields().get(CONTENT_ENCODING))) {
+        if (this.isGzip(headers.get(CONTENT_ENCODING))) {
           stream = new GZIPInputStream(connection.getInputStream());
-        } else if (this.isDeflate(connection.getHeaderFields().get(CONTENT_ENCODING))) {
+        } else if (this.isDeflate(headers.get(CONTENT_ENCODING))) {
           stream = new InflaterInputStream(connection.getInputStream());
         } else {
           stream = connection.getInputStream();
diff --git a/core/src/test/java/feign/client/DefaultClientTest.java b/core/src/test/java/feign/client/DefaultClientTest.java
index 898902e03..7ba7bedb3 100644
--- a/core/src/test/java/feign/client/DefaultClientTest.java
+++ b/core/src/test/java/feign/client/DefaultClientTest.java
@@ -170,6 +170,25 @@ public void canSupportGzip() throws Exception {
 
   }
 
+  @Test
+  public void canExeptCaseInsensitiveHeader() throws Exception {
+    /* enqueue a zipped response */
+    final String responseData = "Compressed Data";
+    server.enqueue(new MockResponse()
+        .addHeader("content-encoding", "gzip")
+        .setBody(new Buffer().write(compress(responseData))));
+
+    TestInterface api = newBuilder()
+        .target(TestInterface.class, "http://localhost:" + server.getPort());
+
+    String result = api.get();
+
+    /* verify that the response is unzipped */
+    assertThat(result).isNotNull()
+        .isEqualToIgnoringCase(responseData);
+
+  }
+
   @Test
   public void canSupportDeflate() throws Exception {
     /* enqueue a zipped response */

From 0295166f1966436724b98623d96a86f6149d5aa6 Mon Sep 17 00:00:00 2001
From: Alexander Zadvinskiy <azadvinskiy@it-one.ru>
Date: Fri, 4 Mar 2022 18:17:30 +0300
Subject: [PATCH 2/2] Add ability use case insensitive headers for default
 Client

---
 core/src/main/java/feign/Client.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/src/main/java/feign/Client.java b/core/src/main/java/feign/Client.java
index b52d1cd30..885fac861 100644
--- a/core/src/main/java/feign/Client.java
+++ b/core/src/main/java/feign/Client.java
@@ -115,7 +115,7 @@ Response convertResponse(HttpURLConnection connection, Request request) throws I
             connection.getRequestMethod(), connection.getURL()));
       }
 
-      Map<String, Collection<String>> headers =  new TreeMap<>(CASE_INSENSITIVE_ORDER);
+      Map<String, Collection<String>> headers = new TreeMap<>(CASE_INSENSITIVE_ORDER);
       for (Map.Entry<String, List<String>> field : connection.getHeaderFields().entrySet()) {
         // response message
         if (field.getKey() != null) {