[[2]] Localhost (127.0.0.1) may also be unavailable if the whole
        network stack is offline.

  [[3]] "Remote" repositories referenced using the file:// protocol may
        be available. However, if that file:// url references a
        file-share, as in the case of an NFS or SMB mount, that will
        be unavailable.

  So, offline mode has several implications, some of which may not be
  altogether obvious:

            <build>
                <plugins>
                    <plugin>
                        <!--
                        The goal is to sign all artifacts so that the user may verify them before downloading.
                        The automatic build system may reuire your key ID, and passphrase specified using system properties:
                        -Dgpg.passphrase="<passphrase>" -Dgpg.keyname="<your key ID>"