code: public static <T> Position.Readable<T> readOnly(final Type type, final T value) {
          Validate.isTrue(TypeUtils.isInstance(value, type), "%s is not an instance of %s", value, Types.toString(type));
          return readOnly(type, () -> value);
      }
docs: Get a read-only position of type {@code type} and value {@code value}.
  
  @param type not {@code null}
  @param value
  @return Position.Readable