Actually, it looks like they've shipped as:
/* PHP CODE HERE */
/* BODY HERE */
$body = <<<EOF
EOF;
Since at least 753 (oldest build I have loaded on my file server); the system generates new islands as the expected:
/* PHP CODE HERE, IF NECESSARY */
/* DO NOT CHANGE THE LINE BELOW */
$body = <<<EOF
Body of the custom box here
EOF;
/* DO NOT CHANGE THE LINE ABOVE */
Note that this would only affect new installs, as a basic upgrade step is to not upload the folder.
All examples of the Custom Islands at UBBDev or on UBBWiki all reference the later. But, as previously mentioned, you'll still need to add the body eof coding to your CI.
We'll look at updating the default comments on the stock Custom Islands, to bring them in line with how the system generates new entries.