refactor: amend message generation in AppiumFluentWait

Co-authored-by: Valery Yatsynovich <[email protected]>

Author: AlessandroMiccoli

src/main/java/io/appium/java_client/AppiumFluentWait.java

@@ -258,12 +258,11 @@ private <V> V performIteration(Function<? super T, V> isTrue, Instant start, Ins
     }
 
     private <V> void handleTimeoutException(Throwable lastException, Function<? super T, V> isTrue) {
-        String message = getMessageSupplier() != null ? getMessageSupplier().get() : null;
-        String waitingMessage = message != null ? message : "waiting for " + isTrue;
+        String message = Optional.ofNullable(getMessageSupplier()).map(Supplier::get).orElseGet(() -> "waiting for " + isTrue);
 
         String timeoutMessage = String.format(
                 "Expected condition failed: %s (tried for %s millis with an interval of %s millis)",
-                waitingMessage,
+                message,
                 getTimeout().toMillis(),
                 getInterval().toMillis()
         );