import lombok.ExtensionMethod; @ExtensionMethod(ExtensionMethodPrimitives.Primitives.class) class ExtensionMethodPrimitives { static class Primitives { Primitives() { super(); } public static int toInt(final byte in) { return (in & 0xff); } } ExtensionMethodPrimitives() { super(); } private void test(final byte b) { int i = ExtensionMethodPrimitives.Primitives.toInt(b); } }