Quirk: Integer cache and == on boxed numbers #88

Goal: explain why Integer a = 127, b = 127; a == b is true but fails for 128.

Show:

• the -128..127 cache from Integer.valueOf (autoboxing) vs new Integer (deprecated)
• same behaviour for Long, Short, Byte, Character (0..127); none for Double/Float
• the fix: equals / unboxing; NPE when unboxing null

Where: new package FirstSteps/src/test/java/pl/mperor/lab/java/quirk