@Override
                  public String load(String key) throws Exception {
                    return lookupKey(key);
                  }
Store keys and secrets in a cache so we can reduce load on cloud storage / KMS when reading
keys and reading/decrypting secrets several times on startup.

<p>Set the cache to reload keys/secrets periodically so that in the event of a key/secret being
compromised, we can update them without restarting our servers.
extensions/cloud/portability-cloud-google/src/main/java/org/datatransferproject/cloud/google/GoogleAppCredentialStore.java