Method checkStringList

core/src/main/java/io/grpc/internal/JsonUtil.java:286–297

Casts a list of unchecked JSON values to a list of String. If the given list contains a value that is not a String, throws an exception.

(List<?> rawList)

   * contains a value that is not a String, throws an exception.
   */
  @SuppressWarnings("unchecked")
  public static List<String> checkStringList(List<?> rawList) {
    for (int i = 0; i < rawList.size(); i++) {
      if (!(rawList.get(i) instanceof String)) {
        throw new ClassCastException(
            String.format(
                Locale.US,
                "value '%s' for idx %d in '%s' is not string", rawList.get(i), i, rawList));
      }
    }
    return (List<String>) rawList;
  }

  private static final long DURATION_SECONDS_MIN = -315576000000L;
  private static final long DURATION_SECONDS_MAX = 315576000000L;