Fix the port and the javadoc building inside a nix devShell

Author: coltfred

examples/cached-key-example/src/main/java/com/ironcorelabs/cachedkey/CachedKeyExample.java

@@ -15,7 +15,7 @@
  */
 public class CachedKeyExample {
 
-  private static final String TSP_ADDR = "http://localhost:7777";
+  private static final String TSP_ADDR = "http://localhost:32804";
 
   public static void main(String[] args) throws Exception {
 

flake.nix

@@ -13,6 +13,10 @@
             maven
             openjdk17
           ];
+          # Nix sets SOURCE_DATE_EPOCH to 1980-01-01T00:00:00Z (315532800) for
+          # reproducible builds, but maven-javadoc-plugin requires at least
+          # 1980-01-01T00:00:02Z. Bump by 2 seconds to satisfy the validation.
+          SOURCE_DATE_EPOCH = 315532802;
         };
       }
     );