#1317 Special Case Pattern (#1624)

* #1317 Add Special Case Pattern

To focus on pattern itself, I implement DB and
maintenance lock by the singleton instance.

* #1317 Add special cases unit tests

Assert the logger output
(ref: https://stackoverflow.com/a/52229629)

* #1317 Add README.md

Add Special Case Pattern README

* #1317 Format: add a new line to end of file

Co-authored-by: Subhrodip Mohanta <subhrodipmohanta@gmail.com>

special-case/src/main/java/com/iluwatar/specialcase/MoneyTransaction.java

@@ -0,0 +1,12 @@
+package com.iluwatar.specialcase;
+
+public class MoneyTransaction {
+
+  private Double amount;
+  private Double price;
+
+  public MoneyTransaction(Double amount, Double price) {
+    this.amount = amount;
+    this.price = price;
+  }
+}