docs: @Pure
  	public static <T> String join(char leftSeparator, char rightSeparator, @SuppressWarnings("unchecked") T... strs) {
  		final StringBuilder buffer = new StringBuilder();
  		for (final Object s : strs) {
  			buffer.append(leftSeparator);
  			if (s != null) {
  				buffer.append(s.toString());
  			}
  			buffer.append(rightSeparator);
  		}
  		return buffer.toString();
  	}