code: public void provideExpirationWarnings(int daysBeforeExpireWarning, String keyStoreName) throws Exception {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              Tr.entry(tc, "provideExpirationWarnings", Integer.valueOf(daysBeforeExpireWarning));
  
          KeyStore keystore = getKeyStore(false, false);
  
          if (keystore != null) {
              try {
                  Enumeration<String> e = keystore.aliases();
                  if (e != null) {
                      for (; e.hasMoreElements();) {
                          String alias = e.nextElement();
                          if (null == alias)
                              continue;
                          Certificate[] cert_chain = keystore.getCertificateChain(alias);
                          if (null == cert_chain)
                              continue;
                          for (int i = 0; i < cert_chain.length; i++) {
                              printWarning(daysBeforeExpireWarning, keyStoreName, alias, (X509Certificate) cert_chain[i]);
                          }
                      }
                  }
              } catch (Exception e) {
                  if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled())
                      Tr.debug(tc, "Exception validating KeyStore expirations; " + e);
                  FFDCFilter.processException(e, getClass().getName(), "provideExpirationWarnings", this);
                  throw e;
              }
          }
  
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              Tr.exit(tc, "provideExpirationWarnings");
      }
docs: Cycle through the keystore looking for expired certificates. Print a
  warning for any certificates that are expired or will expire during the
  input interval.
  
  @param daysBeforeExpireWarning
  @param keyStoreName
  @throws Exception