refactor: Refactor monitor patterns example code (#2560)

* feat:adjust the interval of amount because it is not reasonable before and add condition when transfer TianLeZhou 9 minutes ago

* feat:add ReturnBalanceWhenGivenAccountNumber test

* feat:adjust order of import package

monitor/src/test/java/com/iluwatar/monitor/BankTest.java

@@ -69,4 +69,11 @@ class BankTest {
   void BalanceHaveToBeOK() {
     assertEquals(4000, bank.getBalance());
   }
+
+  @Test
+  void ReturnBalanceWhenGivenAccountNumber() {
+    bank.transfer(0, 1, 1000);
+    assertEquals(0, bank.getBalance(0));
+    assertEquals(2000, bank.getBalance(1));
+  }
 }