code: public static <T> Position.Readable<T> readOnly(final Type type, final Supplier<T> supplier) {
          return new RO<>(Validate.notNull(type, "type"), Validate.notNull(supplier, "supplier"));
      }
docs: Get a read-only position of type {@code type}, obtaining its value from {@code supplier}.
  
  @param type not {@code null}
  @param supplier not {@code null}
  @return Position.Readable