In example examples.confd\intro\java\12-maapi the callpoint is not YANG action callpoint, but clispec callpoint, found in commands-c.cli.
Example how to use actions is in examples.confd/intro/java/7-actions/config.yang. The tailf:action is present inside YANG file. If you have yang file that cannot be modified, you can write action into separate annotation file and annotate it. See ConfD user guide, YNAG chapter - Using a YANG annotation file and tailf:annotation statement.