Jwt.Builder#notBefore Value Is Instant

Fixes gh-7442

Author: jzheaux

oauth2/oauth2-jose/src/main/java/org/springframework/security/oauth2/jwt/Jwt.java

@@ -234,7 +234,7 @@ public Builder issuer(String issuer) {
 		 * @return the {@link Builder} for further configurations
 		 */
 		public Builder notBefore(Instant notBefore) {
-			this.claim(NBF, notBefore.getEpochSecond());
+			this.claim(NBF, notBefore);
 			return this;
 		}