import lombok.experimental.ExtensionMethod; @ExtensionMethod({ExtensionMethodAutoboxing.Extensions.class}) class ExtensionMethodAutoboxing { static class Extensions { Extensions() { super(); } public static String boxing(String string, Long a, int b) { return ((((string + " ") + a) + " ") + b); } } ExtensionMethodAutoboxing() { super(); } public void test() { Long l1 = 1l; long l2 = 1l; Integer i1 = 1; int i2 = 1; String string = "test"; ExtensionMethodAutoboxing.Extensions.boxing(string, l1, i1); ExtensionMethodAutoboxing.Extensions.boxing(string, l1, i2); ExtensionMethodAutoboxing.Extensions.boxing(string, l2, i1); ExtensionMethodAutoboxing.Extensions.boxing(string, l2, i2); } }