Update google-auth-library-java/oauth2_http/javatests/com/google/auth/oauth2/IdTokenCredentialsTest.java

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: westarle

google-auth-library-java/oauth2_http/javatests/com/google/auth/oauth2/IdTokenCredentialsTest.java

@@ -129,13 +129,7 @@ void caching() throws IOException {
             .setIdTokenProvider(mockProvider)
             .setTargetAudience("https://foo.bar")
             .build();
-    credentials.clock =
-        new Clock() {
-          @Override
-          public long currentTimeMillis() {
-            return 1564471451000L; // 2019-07-30T08:24:11Z (STANDARD_ID_TOKEN iat)
-          }
-        };
+    credentials.clock = () -> 1564471451000L; // 2019-07-30T08:24:11Z (STANDARD_ID_TOKEN iat)
 
     credentials.refreshIfExpired();
     credentials.refreshIfExpired();