Fixed extracting charset from response.

core/src/main/java/feign/FeignException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 The Feign Authors
+ * Copyright 2012-2024 The Feign Authors
  *
  * 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
@@ -21,6 +21,7 @@
 import java.nio.ByteBuffer;
 import java.nio.CharBuffer;
 import java.nio.charset.Charset;
+import java.nio.charset.IllegalCharsetNameException;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Map;
@@ -29,6 +30,7 @@
 import java.util.regex.Pattern;
 import static feign.Util.*;
 import static java.lang.String.format;
+import static java.util.regex.Pattern.CASE_INSENSITIVE;
 
 /**
  * Origin exception type for all Http Apis.
@@ -519,14 +521,18 @@ private static Charset getResponseCharset(Map<String, Collection<String>> header
         return null;
       }
 
-      Pattern pattern = Pattern.compile(".*charset=([^\\s|^;]+).*");
+      Pattern pattern = Pattern.compile(".*charset=\"?([^\\s|^;|^\"]+).*", CASE_INSENSITIVE);
       Matcher matcher = pattern.matcher(strings.iterator().next());
       if (!matcher.lookingAt()) {
         return null;
       }
 
       String group = matcher.group(1);
-      if (!Charset.isSupported(group)) {
+      try {
+        if (!Charset.isSupported(group)) {
+          return null;
+        }
+      } catch (IllegalCharsetNameException ex) {
         return null;
       }
       return Charset.forName(group);

core/src/test/java/feign/FeignExceptionTest.java

@@ -24,6 +24,8 @@
 import java.util.HashMap;
 import java.util.Map;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
 
 class FeignExceptionTest {
 
@@ -76,6 +78,32 @@ void createFeignExceptionWithCorrectCharsetResponse() {
         .isEqualTo("[400] during [GET] to [/home] [methodKey]: [response]");
   }
 
+  @ParameterizedTest
+  @ValueSource(strings = {
+      "application/json;charset=\"UTF-16BE\"",
+      "application/json; charset=UTF-16BE",
+      "application/json; charset=\"UTF-16BE\"",
+      "application/json;charset=UTF-16BE"
+  })
+  void createFeignExceptionWithCorrectCharsetResponseButDifferentContentTypeFormats(String contentType) {
+    Map<String, Collection<String>> map = new HashMap<>();
+    map.put("connection", new ArrayList<>(Collections.singletonList("keep-alive")));
+    map.put("content-length", new ArrayList<>(Collections.singletonList("100")));
+    map.put("content-type",
+        new ArrayList<>(Collections.singletonList(contentType)));
+
+    Request request = Request.create(Request.HttpMethod.GET, "/home", Collections.emptyMap(),
+        "data".getBytes(StandardCharsets.UTF_16BE), StandardCharsets.UTF_16BE, null);
+
+    Response response =
+        Response.builder().status(400).body("response".getBytes(StandardCharsets.UTF_16BE))
+            .headers(map).request(request).build();
+
+    FeignException exception = FeignException.errorStatus("methodKey", response);
+    assertThat(exception.getMessage())
+        .isEqualTo("[400] during [GET] to [/home] [methodKey]: [response]");
+  }
+
   @Test
   void createFeignExceptionWithErrorCharsetResponse() {
     Map<String, Collection<String>> map = new HashMap<>();