There are multiple problems related to JavaDoc inline tags embedded in HTML attribute values. Inline tags are parsed in HTML attribute values because we support the `{@docRoot}` tag to insert the relative URL of the documentation root. However, other usages of `{@` inside attribute values yield strange or buggy behaviour.

 - Escaped inline tag sequences starting with `{@@` cause `{@` to be added to the parsed string, but further characters are not added to the parsed attribute value.
 - Unknown inline tags are accepted and ignored without warning or error.
 - Known inline tags are accepted and processed, even if they produce output that is invalid in the context of an HTML attribute value (such as `{@index}` or `{@link}` tags generating HTML flow content).

Items 1 and 2 only occur with traditional doc comments, while item 3 also affects Markdown doc comments.