From javadoc-dev:

Hello and Merry Christmas,

I discovered this odd javac behavior with jdk8 up to jdk15 (didn't
check the latest head). This source file (note the anchor tag over
multiple lines):

/**
 * Lucene internals or asking for help on <a
 * href="mailto:java-user at lucene.apache.org">java-user at lucene.apache.org</a>
  */
public class Breaks {}

When compiled with

javac -Xdoclint:all/protected Breaks.java

generates this:

Breaks.java:2: error: malformed HTML
 * Lucene internals or asking for help on <a
                                          ^
Breaks.java:3: error: bad use of '>'
 * href="mailto:java-user at lucene.apache.org">java-user at lucene.apache.org</a>
                                            ^
Breaks.java:3: error: unexpected end tag: </a>
 * href="mailto:java-user at lucene.apache.org">java-user at lucene.apache.org</a>
                                                                        ^
What's interesting is that the following two alternatives compile just fine:

/**
 * Lucene internals or asking for help on <a
 * href="http://lucene.apache.org">java-user at lucene.apache.org</a>
  */
public class Passes {}

/**
 * Lucene internals or asking for help on <a
href="mailto:java-user at lucene.apache.org">java-user at lucene.apache.org</a>
to figure out why.
  */
public class Passes2 {}

Is it just me or all these should compile just fine?...

Dawid

[1] Just in case mail clients attempt to reformat the pasted examples,
here's a gist with
the sources:
https://gist.github.com/dweiss/c1c9f218c6a8e5d2f253193806a9f472