docs: protected void append(Object object, String indentation, int index) {
  		if (indentation.length() == 0) {
  			append(object, index);
  			return;
  		}
  		if (object == null)
  			return;
  		if (object instanceof String) {
  			append(indentation, (String)object, index);
  		} else if (object instanceof StringConcatenation) {
  			StringConcatenation other = (StringConcatenation) object;
  			List<String> otherSegments = other.getSignificantContent();
  			appendSegments(indentation, index, otherSegments, other.lineDelimiter);
  		} else if (object instanceof StringConcatenationClient) {
  			StringConcatenationClient other = (StringConcatenationClient) object;
  			other.appendTo(new IndentedTarget(this, indentation, index));
  		} else {
  			final String text = getStringRepresentation(object);
  			if (text != null) {
  				append(indentation, text, index);
  			}
  		}
  	}