Headers substitutions were not being expanded by the value name, instead it was using the header name..

Author: jdamick

core/src/main/java/feign/RequestTemplate.java

@@ -205,7 +205,7 @@ public RequestTemplate resolve(Map<String, ?> unencoded) {
       for (String value : valuesOrEmpty(headers, field)) {
         String resolved;
         if (value.indexOf('{') == 0) {
-          resolved = String.valueOf(unencoded.get(field));
+          resolved = expand(value, unencoded);
         } else {
           resolved = value;
         }

core/src/test/java/feign/DefaultContractTest.java

@@ -245,10 +245,10 @@ public void headerParamsParseIntoIndexToName() throws Exception {
             HeaderParams.class.getDeclaredMethod("logout", String.class));
 
     assertThat(md.template())
-        .hasHeaders(entry("Auth-Token", asList("{Auth-Token}", "Foo")));
+        .hasHeaders(entry("Auth-Token", asList("{authToken}", "Foo")));
 
     assertThat(md.indexToName())
-        .containsExactly(entry(0, asList("Auth-Token")));
+        .containsExactly(entry(0, asList("authToken")));
   }
 
   @Test
@@ -343,8 +343,8 @@ void login(
   interface HeaderParams {
 
     @RequestLine("POST /")
-    @Headers({"Auth-Token: {Auth-Token}", "Auth-Token: Foo"})
-    void logout(@Param("Auth-Token") String token);
+    @Headers({"Auth-Token: {authToken}", "Auth-Token: Foo"})
+    void logout(@Param("authToken") String token);
   }
 
   interface CustomExpander {

core/src/test/java/feign/RequestTemplateTest.java

@@ -126,6 +126,17 @@ public void resolveTemplateWithBaseAndParameterizedIterableQuery() {
         );
   }
 
+  @Test
+  public void resolveTemplateWithHeaderSubstitutions() {
+    RequestTemplate template = new RequestTemplate().method("GET")
+        .header("Auth-Token", "{authToken}");
+
+    template.resolve(mapOf("authToken", "1234"));
+
+    assertThat(template)
+        .hasHeaders(entry("Auth-Token", asList("1234")));
+  }
+
   @Test
   public void resolveTemplateWithMixedRequestLineParams() throws Exception {
     RequestTemplate template = new RequestTemplate().method("GET")//