Overriding System time for testing (#4779)

* Overriding System time for testing

* Remove Joda Date Time examples

core-java-8/src/main/java/com/baeldung/aspect/ChangeCallsToCurrentTimeInMillisMethod.aj

@@ -0,0 +1,9 @@
+package com.baeldung.aspect;
+
+public aspect ChangeCallsToCurrentTimeInMillisMethod {
+    long around():
+            call(public static native long java.lang.System.currentTimeMillis())
+                    && within(user.code.base.pckg.*) {
+        return 0;
+    }
+}

core-java-8/src/test/java/com/baeldung/util/CurrentDateTimeUnitTest.java

@@ -1,6 +1,7 @@
 package com.baeldung.util;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 import java.time.Clock;
 import java.time.Instant;
@@ -9,6 +10,8 @@ import java.time.LocalTime;
 import java.time.ZoneId;
 import java.time.temporal.ChronoField;
 
+import org.joda.time.DateTime;
+import org.joda.time.DateTimeUtils;
 import org.junit.Test;
 
 public class CurrentDateTimeUnitTest {
@@ -39,5 +42,4 @@ public class CurrentDateTimeUnitTest {
 
         assertEquals(clock.instant().getEpochSecond(), now.getEpochSecond());
     }
-
 }