upgrade to gradle 7.1, java 16, javafx 16

src/main/java/com/sparrowwallet/sparrow/io/IOUtils.java

@@ -90,7 +90,9 @@ public class IOUtils {
                         // if it is a subdirectory, we just return the directory name
                         entry = entry.substring(0, checkSubdir);
                     }
-                    result.add(entry);
+                    if(!entry.isEmpty()) {
+                        result.add(entry);
+                    }
                 }
             }
 

src/main/java/com/sparrowwallet/sparrow/net/ElectrumServer.java

@@ -1,7 +1,6 @@
 package com.sparrowwallet.sparrow.net;
 
 import com.github.arteam.simplejsonrpc.client.Transport;
-import com.google.common.collect.Iterables;
 import com.google.common.eventbus.Subscribe;
 import com.google.common.net.HostAndPort;
 import com.sparrowwallet.drongo.KeyPurpose;

src/main/java/com/sparrowwallet/sparrow/preferences/ServerPreferencesController.java

@@ -22,7 +22,6 @@ import javafx.stage.DirectoryChooser;
 import javafx.stage.FileChooser;
 import javafx.stage.Stage;
 import javafx.util.Duration;
-import net.freehaven.tor.control.TorControlError;
 import org.berndpruenster.netlayer.tor.Tor;
 import org.controlsfx.control.SegmentedButton;
 import org.controlsfx.glyphfont.Glyph;

src/main/java/com/sparrowwallet/sparrow/transaction/HeadersController.java

@@ -19,7 +19,6 @@ import com.sparrowwallet.sparrow.io.Device;
 import com.sparrowwallet.sparrow.net.ElectrumServer;
 import com.sparrowwallet.sparrow.io.Storage;
 import com.sparrowwallet.sparrow.payjoin.Payjoin;
-import com.sparrowwallet.sparrow.payjoin.PayjoinReceiverException;
 import com.sparrowwallet.sparrow.wallet.Entry;
 import com.sparrowwallet.sparrow.wallet.HashIndexEntry;
 import com.sparrowwallet.sparrow.wallet.TransactionEntry;