version 1.0

src/main/java/module-info.java

@@ -1,9 +1,10 @@
 import net.woggioni.gbcs.url.ClasspathUrlStreamHandlerFactoryProvider;
 
-module net.woggioni.gbcs {
+open module net.woggioni.gbcs {
     requires java.sql;
     requires java.xml;
     requires java.logging;
+    requires java.naming;
     requires kotlin.stdlib;
     requires io.netty.buffer;
     requires io.netty.transport;

src/main/java/net/woggioni/gbcs/url/ClasspathUrlStreamHandlerFactoryProvider.java

@@ -1,10 +1,13 @@
 package net.woggioni.gbcs.url;
 
+import net.woggioni.jwo.Fun;
+
 import java.io.IOException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.net.URLStreamHandler;
 import java.net.URLStreamHandlerFactory;
+import java.util.Optional;
 
 public class ClasspathUrlStreamHandlerFactoryProvider implements URLStreamHandlerFactory {
 
@@ -22,7 +25,9 @@ public class ClasspathUrlStreamHandlerFactoryProvider implements URLStreamHandle
         @Override
         protected URLConnection openConnection(URL u) throws IOException {
             final URL resourceUrl = classLoader.getResource(u.getPath());
-            return resourceUrl.openConnection();
+            return Optional.ofNullable(resourceUrl)
+                    .map((Fun<URL, URLConnection>) URL::openConnection)
+                    .orElseThrow(IOException::new);
         }
     }