code: private int nextBoundaryAfter(int startIndex) {
          BreakIterator breakiterator = search_.breakIter();
  
          if (breakiterator == null) {
              breakiterator = search_.internalBreakIter_;
          }
  
          if (breakiterator != null) {
              return breakiterator.following(startIndex);
          }
  
          return startIndex;
      }
docs: /*
  Find the next break boundary after startIndex. If the UStringSearch object
  has an external break iterator, use that. Otherwise use the internal character
  break iterator.