Simplify ObjectUtils#unwrapOptional

This commit replaces optional.isEmpty() and optional.get() with
optional.orElse(null) for better efficiency and readability.

Closes gh-33612

Author: SungbinYang

spring-core/src/main/java/org/springframework/util/ObjectUtils.java

@@ -173,10 +173,7 @@ public static boolean isEmpty(@Nullable Object obj) {
 	@Nullable
 	public static Object unwrapOptional(@Nullable Object obj) {
 		if (obj instanceof Optional<?> optional) {
-			if (optional.isEmpty()) {
-				return null;
-			}
-			Object result = optional.get();
+			Object result = optional.orElse(null);
 			Assert.isTrue(!(result instanceof Optional), "Multi-level Optional usage not supported");
 			return result;
 		}