Pr/1235 Review (#1250)

* Add simple implementation for strangler pattern.

* Add strangler pattern in pom.xml.

* change package name

* Revert "change package name"

This reverts commit 430bd9073ea7bea6430586a0953c77f1798aacc8.

* Code review for strangler

Delete final of method parameters.
Add final to private members.
Change package name.

* Revert "Code review for strangler"

This reverts commit d5063567083e0348d678a938bd749e17343bcb8e.

* Revert "Revert "Code review for strangler""

This reverts commit c8fd65fda782749c4f74f6de85da0f271d3c48a8.

* Remove unnecessary files

strangler/etc/strangler.puml

@@ -0,0 +1,61 @@
+@startuml
+
+package com.iluwatar.strangler {
+    class App {
+        + main(args : String[]) {static}
+    }
+
+    class OldArithmetic {
+        - LOGGER : Logger {static}
+        - VERSION : String {static}
+        - source : OldSource
+        + sum(nums : int...)
+        + mul(nums : int...)
+    }
+
+    class HalfArithmetic {
+        - LOGGER : Logger {static}
+        - VERSION : String {static}
+        - oldSource : OldSource
+        - newSource : HalfSource
+        + sum(nums : int...)
+        + mul(nums : int...)
+        + ifHasZero(nums : int...)
+    }
+
+    class NewArithmetic {
+        - LOGGER : Logger {static}
+        - VERSION : String {static}
+        - source : NewSource
+        + sum(nums : int...)
+        + mul(nums : int...)
+        + ifHasZero(nums : int...)
+    }
+
+    class OldSource {
+        - LOGGER : Logger {static}
+        - VERSION : String {static}
+        + accumulateSum(nums : int...)
+        + accumulateMul(nums : int...)
+    }
+
+    class HalfSource {
+        - LOGGER : Logger {static}
+        - VERSION : String {static}
+        + accumulateSum(nums : int...)
+        + ifNonZero(nums : int...)
+    }
+
+    class NewSource {
+        - LOGGER : Logger {static}
+        - VERSION : String {static}
+        + accumulateSum(nums : int...)
+        + accumulateMul(nums : int...)
+        + ifNonZero(nums : int...)
+    }
+}
+OldArithmetic o--> OldSource
+HalfArithmetic o--> OldSource
+HalfArithmetic o--> HalfSource
+NewArithmetic o--> NewSource
+@enduml