Class AuthenticationInterceptor instead of lambda

Author: hosuaby

oauth2/src/main/java/feign/auth/oauth2/OAuth2Authentication.java

@@ -82,11 +82,7 @@ public <B extends BaseBuilder<B, T>, T> B beforeBuild(final B baseBuilder) {
     idpClient = new OAuth2IDPClient(httpClient, httpOptions, jsonDecoder);
 
     return baseBuilder
-        .requestInterceptor(
-            (final RequestTemplate requestTemplate) -> {
-              final String accessToken = getAccessToken();
-              requestTemplate.header("Authorization", "Bearer " + accessToken);
-            })
+        .requestInterceptor(new AuthenticationInterceptor())
         .retryer(new UnauthorizedRetryer())
         .errorDecoder(UnauthorizedErrorDecoder.INSTANCE);
   }
@@ -119,6 +115,15 @@ private synchronized String forceAuthentication() {
     return oAuth2TokenResponse.getAccessToken();
   }
 
+  final class AuthenticationInterceptor implements RequestInterceptor {
+
+    @Override
+    public void apply(final RequestTemplate requestTemplate) {
+      final String accessToken = getAccessToken();
+      requestTemplate.header("Authorization", "Bearer " + accessToken);
+    }
+  }
+
   final class UnauthorizedRetryer implements Retryer {
     private boolean reauthenticated = false;