Do not convert @Header name when the name is specified (#5841)

Motivation:
We must not convert the header name specified in `@Header` when creating an annotated service.
This is a regression introduced by #5547, affecting 1.29.0 through 1.29.3.

Modifications:
- Do not convert the header name specified in `@Header`.

Result:
- An annotated service that has a `@Header` with the specified name now works correctly.

core/src/main/java/com/linecorp/armeria/internal/server/annotation/AnnotatedElementNameUtil.java

@@ -31,9 +31,9 @@
 final class AnnotatedElementNameUtil {
 
     /**
-     * Returns the value of {@link Header}, {@link Param}, {@link Attribute} if the value is not blank.
+     * Returns the value of {@link Param}, {@link Attribute} if the value is not blank.
      * If the value is blank, it returns the name of the specified {@code nameRetrievalTarget} object
-     * which is an instance of {@link Header}, {@link Param}, {@link Attribute} or {@link Field}.
+     * which is an instance of {@link Param}, {@link Attribute} or {@link Field}.
      */
     static String findName(Object nameRetrievalTarget, String value) {
         requireNonNull(nameRetrievalTarget, "nameRetrievalTarget");
@@ -44,6 +44,27 @@ static String findName(Object nameRetrievalTarget, String value) {
         return getName(nameRetrievalTarget);
     }
 
+    /**
+     * Returns the value of the {@link Header} annotation which is specified on the {@code element} if
+     * the value is not blank. If the value is blank, it returns the name of the specified
+     * {@code nameRetrievalTarget} object which is an instance of {@link Parameter} or {@link Field}.
+     *
+     * <p>Note that the name of the specified {@code nameRetrievalTarget} will be converted as
+     * {@link CaseFormat#LOWER_HYPHEN} that the string elements are separated with one hyphen({@code -})
+     * character. The value of the {@link Header} annotation will not be converted because it is clearly
+     * specified by a user.
+     */
+    static String findName(Header header, Object nameRetrievalTarget) {
+        requireNonNull(nameRetrievalTarget, "nameRetrievalTarget");
+
+        final String value = header.value();
+        if (DefaultValues.isSpecified(value)) {
+            checkArgument(!value.isEmpty(), "value is empty.");
+            return value;
+        }
+        return toHeaderName(getName(nameRetrievalTarget));
+    }
+
     /**
      * Returns the name of the specified element or the default name if it can't get.
      */

core/src/main/java/com/linecorp/armeria/internal/server/annotation/AnnotatedValueResolver.java

@@ -22,7 +22,6 @@
 import static com.linecorp.armeria.internal.server.annotation.AnnotatedElementNameUtil.findName;
 import static com.linecorp.armeria.internal.server.annotation.AnnotatedElementNameUtil.getName;
 import static com.linecorp.armeria.internal.server.annotation.AnnotatedElementNameUtil.getNameOrDefault;
-import static com.linecorp.armeria.internal.server.annotation.AnnotatedElementNameUtil.toHeaderName;
 import static com.linecorp.armeria.internal.server.annotation.AnnotatedServiceFactory.findDescription;
 import static com.linecorp.armeria.internal.server.annotation.AnnotatedServiceTypeUtil.stringToType;
 import static com.linecorp.armeria.internal.server.annotation.DefaultValues.getSpecifiedValue;
@@ -471,7 +470,7 @@ private static AnnotatedValueResolver of(AnnotatedElement annotatedElement,
 
         final Header header = annotatedElement.getAnnotation(Header.class);
         if (header != null) {
-            final String name = toHeaderName(findName(typeElement, header.value()));
+            final String name = findName(header, typeElement);
             return ofHeader(name, annotatedElement, typeElement, type, description);
         }
 

core/src/test/java/com/linecorp/armeria/internal/server/annotation/AnnotatedServiceTest.java

@@ -773,6 +773,12 @@ public String customHeader5(@Header List<Integer> numbers,
                    String.join(":", strings);
         }
 
+        @Post("/headerNameSpecified")
+        public String headerNameSpecified(@Header("X-x-FoO-bAr") String id) {
+            // Because the header name is specified, it's not converted.
+            return id;
+        }
+
         @Get("/headerDefault")
         public String headerDefault(RequestContext ctx,
                                     @Header @Default("hello") String username,
@@ -1224,6 +1230,10 @@ void testRequestHeaderInjection() throws Exception {
             request.addHeader("strings", "minwoox");
             testBody(hc, request, "1:2:1/minwoox:giraffe");
 
+            request = post("/11/headerNameSpecified");
+            request.addHeader("X-x-FoO-bAr", "qwerty");
+            testBody(hc, request, "qwerty");
+
             request = get("/11/headerDefault");
             testBody(hc, request, "hello/world/(null)");