[TINKERPOP-3146] Address PR comments

Author: cdegroc

gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/AbstractChannelizer.java

@@ -165,7 +165,7 @@ public void init(final ServerGremlinExecutor serverGremlinExecutor) {
                                 logger.error("Failed to reload SSLFactory", e);
                             }
                         }),
-                        1L, 1L, TimeUnit.MINUTES
+                        settings.ssl.refreshInterval, settings.ssl.refreshInterval, TimeUnit.MILLISECONDS
                 );
             }
         } else {

gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/Settings.java

@@ -581,6 +581,12 @@ public static class SslSettings {
          */
         public ClientAuth needClientAuth = ClientAuth.NONE;
 
+        /**
+         * The interval, in milliseconds, at which the trustStore and keyStore files are checked for updates.
+         * The default interval is 60 seconds.
+         */
+        public long refreshInterval = 60000L;
+
         private SslContext sslContext;
 
         /**

gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/util/SSLStoreFilesModificationWatcher.java

@@ -53,7 +53,7 @@ public class SSLStoreFilesModificationWatcher implements Runnable {
      * @param trustStore             path to the trustStore file or null to ignore
      * @param onModificationRunnable function to run when a modification to the keyStore or trustStore is detected
      */
-    public SSLStoreFilesModificationWatcher(String keyStore, String trustStore, Runnable onModificationRunnable) {
+    public SSLStoreFilesModificationWatcher(final String keyStore, final String trustStore, final Runnable onModificationRunnable) {
         // keyStore/trustStore can be null when not specified in gremlin-server Settings
         this.keyStore = keyStore != null ? Paths.get(keyStore) : null;
         this.trustStore = trustStore != null ? Paths.get(trustStore) : null;
@@ -117,8 +117,8 @@ public void run() {
         }
     }
 
-    private static ZonedDateTime getLastModifiedTime(Path filepath) throws IOException {
+    private static ZonedDateTime getLastModifiedTime(final Path filepath) throws IOException {
         BasicFileAttributes attributes = Files.readAttributes(filepath, BasicFileAttributes.class);
         return ZonedDateTime.ofInstant(attributes.lastModifiedTime().toInstant(), ZoneOffset.UTC);
     }
-}
+}