code: public void append(StringConcatenationClient client, String indentation) {
  		if (indentation.isEmpty()) {
  			append(client);
  		} else if (client != null)
  			client.appendTo(new IndentedTarget(this, indentation, segments.size()));
  	}
docs: Append the contents of a given StringConcatenationClient to this sequence. Does nothing
  if that argument is <code>null</code>. The given indentation will be prepended to each line except
  the first one.
  
  @param client
  the to-be-appended StringConcatenationClient.
  @param indentation
  the indentation string that should be prepended. May not be <code>null</code>.
  @since 2.11