Update to new calling turn info endpoint, add support for turn server ips.

Co-authored-by: Adel Lahlou <adel@signal.com>

core-util/src/main/java/org/signal/core/util/ListUtil.java

@@ -4,6 +4,7 @@ import androidx.annotation.NonNull;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.stream.Stream;
 
@@ -31,4 +32,8 @@ public final class ListUtil {
 
     return concat;
   }
+
+  public static <T> List<T> emptyIfNull(List<T> list) {
+    return list == null ? Collections.emptyList() : list;
+  }
 }