code: public static String[] split(String str, String separatorChars) {
          return splitWorker(str, separatorChars, -1, false);
      }
docs: <p>
  Splits the provided text into an array, separators specified. This is an alternative to using StringTokenizer.
  </p>
  
  <p>
  The separator is not included in the returned String array. Adjacent separators are treated as one separator. For
  more control over the split use the StrTokenizer class.
  </p>
  
  <p>
  A <code>null</code> input String returns <code>null</code>. A <code>null</code> separatorChars splits on
  whitespace.
  </p>
  
  <pre>
  StringUtils.split(null, *)         = null
  StringUtils.split("", *)           = []
  StringUtils.split("abc def", null) = ["abc", "def"]
  StringUtils.split("abc def", " ")  = ["abc", "def"]
  StringUtils.split("abc  def", " ") = ["abc", "def"]
  StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]
  </pre>
  
  @param str the String to parse, may be null
  @param separatorChars the characters used as the delimiters, <code>null</code> splits on whitespace
  @return an array of parsed Strings, <code>null</code> if null String input