Move optional to java-8-core (#5105)

core-java-8/src/main/java/com/baeldung/optional/PersonRepository.java

@@ -0,0 +1,9 @@
+package com.baeldung.optional;
+
+public class PersonRepository {
+
+    public String findNameById(String id) {
+        return id == null ? null : "Name";
+    }
+
+}