code: public static int indexOfAny(final CharSequence cs, final String searchChars) {
          if (isEmpty(cs) || isEmpty(searchChars)) {
              return INDEX_NOT_FOUND;
          }
          return indexOfAny(cs, searchChars.toCharArray());
      }
docs: <p>Search a CharSequence to find the first index of any
  character in the given set of characters.</p>
  
  <p>A {@code null} String will return {@code -1}.
  A {@code null} search string will return {@code -1}.</p>
  
  <pre>
  StringUtils.indexOfAny(null, *)            = -1
  StringUtils.indexOfAny("", *)              = -1
  StringUtils.indexOfAny(*, null)            = -1
  StringUtils.indexOfAny(*, "")              = -1
  StringUtils.indexOfAny("zzabyycdxx", "za") = 0
  StringUtils.indexOfAny("zzabyycdxx", "by") = 3
  StringUtils.indexOfAny("aba","z")          = -1
  </pre>
  
  @param cs  the CharSequence to check, may be null
  @param searchChars  the chars to search for, may be null
  @return the index of any of the chars, -1 if no match or null input
  @since 2.0
  @since 3.0 Changed signature from indexOfAny(String, String) to indexOfAny(CharSequence, String)