URLPermission class is having an issue , inside it's constructor we are calling .toLowerCase() API which converts the chars depending on the locale , in this case Turkish locale replaces upper case 'I' with a non-ascii lower case 'i'.
r:~$ cat URLPermissionTest.java
import java.net.*;
public class URLPermissionTest {
        public static void main(String[] args) throws Exception {
        String title = "https://IOU.COM";
        URL u = new URL(title);
        URLPermission perm = new URLPermission(title);
    }
}
r:~$ java -Duser.language=tr URLPermissionTest
Exception in thread "main" java.lang.IllegalArgumentException: Invalid
characters in hostname
      at java.base/java.net.HostPortrange.toLowerCase(HostPortrange.java:189)
      at java.base/java.net.HostPortrange.<init>(HostPortrange.java:150)
      at
java.base/java.net.URLPermission$Authority.<init>(URLPermission.java:528)
      at java.base/java.net.URLPermission.parseURI(URLPermission.java:496)
      at java.base/java.net.URLPermission.init(URLPermission.java:205)
      at java.base/java.net.URLPermission.<init>(URLPermission.java:185)
      at java.base/java.net.URLPermission.<init>(URLPermission.java:242)
      at URLPermissionTest.main(URLPermissionTest.java:6)

This issue is reproducible on latest JDK , across all release platforms.