See the following text in jaxp/src/java.xml/share/classes/org/w3c/dom/Comment.java

/**
 * This interface inherits from <code>CharacterData</code> and represents the
 * content of a comment, i.e., all the characters between the starting '
 * <code>&lt;!--</code>' and ending '<code>--&gt;</code>'.

javadoc treats the "!" as the end of the first sentence(!) which means you end up with truncated text in various places, such as the entry for Comment in the package summary, as seen here:
http://download.java.net/java/jdk9/docs/api/org/w3c/dom/package-summary.html

The fix is either to change <code>&lt;!--</code> to {@code <!--} or replace ! with its entity equivalent &#33;