docs: public static int countMatches(CharSequence sourceSequence, CharSequence subSequence) {
          if (isEmpty(sourceSequence) || isEmpty(subSequence) || sourceSequence.length() < subSequence.length()) {
              return 0;
          }
  
          int count = 0;
          int sourceSequenceIndex = 0;
          int subSequenceIndex = 0;
  
          while(sourceSequenceIndex < sourceSequence.length()) {
              if(sourceSequence.charAt(sourceSequenceIndex) == subSequence.charAt(subSequenceIndex)) {
                  sourceSequenceIndex++;
                  subSequenceIndex++;
                  while(sourceSequenceIndex < sourceSequence.length() && subSequenceIndex < subSequence.length()) {
                      if(sourceSequence.charAt(sourceSequenceIndex) != subSequence.charAt(subSequenceIndex)) {
                          break;
                      }
                      sourceSequenceIndex++;
                      subSequenceIndex++;
                  }
                  if(subSequenceIndex == subSequence.length()) {
                      count++;
                  }
                  subSequenceIndex = 0;
                  continue;
              }
              sourceSequenceIndex++;
          }
  
          return count;
      }