$ javac src/TimeDemo.java && java TimeDemo     (1.8.0_504)
plusMonths      : 2026-11-20  (original still 2026-10-20)
end of month    : 2026-02-28
days between    : 292
Period          : P6Y7M21D
Duration        : PT2H15M
same instant NY : 2026-10-20 13:05 EDT
old Date month  : new java.util.Date(126, 9, 20) -> month index 9 (October is 9)