docs: @Override
      public void readBlank() {
          char ch = this.text[++this.position];
          if (ch == ':') return;
          if (ch <= ' ') {
              for (;;) {
                  ch = this.text[++this.position];
                  if (ch > ' ') break;
              }
              if (ch == ':') return;
          }
          throw new ConvertException("'" + new String(text) + "'expected a ':' but '" + ch + "'(position = " + position + ") in (" + new String(this.text) + ")");
      }