import lombok.experimental.ExtensionMethod; @ExtensionMethod({java.util.Arrays.class, ExtensionMethodPlain.Extensions.class}) class ExtensionMethodPlain { public String test() { int[] intArray = {5, 3, 8, 2}; intArray.sort(); String iAmNull = null; return iAmNull.or("hELlO, WORlD!".toTitleCase()); } static class Extensions { public static T or(T obj, T ifNull) { return obj != null ? obj : ifNull; } public static String toTitleCase(String in) { if (in.isEmpty()) return in; return "" + Character.toTitleCase(in.charAt(0)) + in.substring(1).toLowerCase(); } } }