docs: public static final int findInt(CharSequence cs, int radix, int beginIndex, int endIndex)
      {
          IntPredicate predicate = null;
          switch (radix)
          {
              case 8:
                  predicate = Primitives::isOctalDigit;
                  break;
              case 10:
                  predicate = Primitives::isDecimalDigit;
                  break;
              case 16:
                  predicate = Primitives::isHexDigit;
                  break;
              default:
                  throw new UnsupportedOperationException("radix "+radix+" not supported");
          }
          int begin = CharSequences.indexOf(cs, predicate, beginIndex);
          int end = CharSequences.indexOf(cs, predicate.negate(), begin);
          return parseInt(cs, radix, begin, endIndex(end, endIndex));
      }