add support for the Retry-After header sent by OpenRSS

commafeed-server/src/main/java/com/commafeed/CommaFeedProducers.java

@@ -1,5 +1,7 @@
 package com.commafeed;
 
+import java.time.InstantSource;
+
 import com.codahale.metrics.MetricRegistry;
 
 import jakarta.enterprise.inject.Produces;
@@ -8,9 +10,16 @@ import jakarta.inject.Singleton;
 @Singleton
 public class CommaFeedProducers {
 
+	@Produces
+	@Singleton
+	public InstantSource instantSource() {
+		return InstantSource.system();
+	}
+
 	@Produces
 	@Singleton
 	public MetricRegistry metricRegistry() {
 		return new MetricRegistry();
 	}
+
 }