FULL PRODUCT VERSION :
java version "1.8.0_05"
Java(TM) SE Runtime Environment (build 1.8.0_05-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.5-b02, mixed mode)


A DESCRIPTION OF THE PROBLEM :
We have some <abbr> tags in our Javadoc.

When running these through the Javadoc tool, we get an error:

    src/java/com/acme/data/file/image/wmf/NonApmWmfImageData.java:19: error: unknown tag: abbr
      * <abbr title="Aldus Placeable Metafile">APM</abbr> header.</p>
           ^

Needless to say, <abbr> is a perfectly valid tag in HTML and is even present in the outdated version of HTML which Javadoc is still generating.

This essentially prevents using the tool to generate documentation. I consider it a regression also, because Java 7 did not do this checking and thus we were able to use the tool.


REGRESSION. Last worked in version 7u60


REPRODUCIBILITY :
This bug can be reproduced always.