code: public static AckErrorCode of(Values value) {
          if (value == Values.SDK_UNKNOWN) {
              throw new IllegalArgumentException("SDK_UNKNOWN cannot be used to create an AckErrorCode. Use the raw value to" +
                                                 "create an AckErrorCode from a string instead");
          }
          return value == null ? null : new AckErrorCode(value, value.toString());
      }
docs: Create a new {@link AckErrorCode} from an enum value.
  
  @param value String value of the error code.
  @return An {@link AckErrorCode} or null if the value was null.