@Override
      public String apply(Number input) {
        if (input instanceof Long) {
          return "0x" + Long.toHexString(input.longValue()) + "L";
        }
        if (input instanceof Integer) {
          return "0x" + Integer.toHexString(input.intValue());
        }
        throw new IllegalArgumentException("unsupported non integer or long " + input);
      }
Built-in operations, functions and accessors.
Planned to be moved to import/implicit resolution
rather that inheritance.
generator/src/org/immutables/generator/Builtins.java