reduced visibility

src/main/java/org/cryptomator/ui/keyloading/hub/DeviceAlreadyExistsException.java

@@ -1,6 +1,12 @@
 package org.cryptomator.ui.keyloading.hub;
 
+import org.cryptomator.cryptolib.api.MasterkeyLoadingFailedException;
+
 /**
  * Thrown, when Hub registerDevice-Request returns with 409
  */
-public class DeviceAlreadyExistsException extends RuntimeException {}
+class DeviceAlreadyExistsException extends MasterkeyLoadingFailedException {
+	public DeviceAlreadyExistsException() {
+		super("Device already registered on this Hub instance");
+	}
+}