docs: private int lengthOfTypePrefix(int type) {
          int length;
          switch (type) {
              case EmailRecipientUtils.BCC:
                  length = 4;
                  break;
              case EmailRecipientUtils.CC:
                  length = 3;
                  break;
              case EmailRecipientUtils.TO:
                  length = 0;
                  break;
              default:
                  throw new IllegalArgumentException("Unknown type prefix: " + type);
          }
          return length;
      }