Filter any whitespaces when entering text in donationkey form.

main/ui/src/main/java/org/cryptomator/ui/preferences/DonationKeyPreferencesController.java

@@ -1,5 +1,6 @@
 package org.cryptomator.ui.preferences;
 
+import com.google.common.base.CharMatcher;
 import org.cryptomator.common.LicenseHolder;
 import org.cryptomator.common.settings.Settings;
 import org.cryptomator.common.settings.UiTheme;
@@ -10,6 +11,7 @@ import javafx.application.Application;
 import javafx.beans.value.ObservableValue;
 import javafx.fxml.FXML;
 import javafx.scene.control.TextArea;
+import javafx.scene.control.TextFormatter;
 
 @PreferencesScoped
 public class DonationKeyPreferencesController implements FxController {
@@ -32,6 +34,15 @@ public class DonationKeyPreferencesController implements FxController {
 	public void initialize() {
 		donationKeyField.setText(licenseHolder.getLicenseKey().orElse(null));
 		donationKeyField.textProperty().addListener(this::registrationKeyChanged);
+		donationKeyField.setTextFormatter(new TextFormatter<>(this::checkVaultNameLength));
+	}
+
+	private TextFormatter.Change checkVaultNameLength(TextFormatter.Change change) {
+		if (change.isContentChange()) {
+			var strippedText = CharMatcher.whitespace().removeFrom(change.getText());
+			change.setText(strippedText);
+		}
+		return change;
 	}
 
 	private void registrationKeyChanged(@SuppressWarnings("unused") ObservableValue<? extends String> observable, @SuppressWarnings("unused") String oldValue, String newValue) {