code: public static <CS extends CharSequence> CS requireNotNullNorEmpty(CS cs, String message) {
          if (isNullOrEmpty(cs)) {
              throw new IllegalArgumentException(message);
          }
          return cs;
      }
docs: Require a {@link CharSequence} to be neither null, nor empty.
  
  @param cs CharSequence
  @param message error message
  @param <CS> CharSequence type
  @return cs