It seems like everybody is moving from http to https as the preferred protocol (good!) BUT:

If I use javadoc -link with http: URLs the output for e.g. java.util.List in """All Implemented Interfaces""" is NOT linkified, whereas with https: it works fine.

I notice today that attempting to visit
http://docs.oracle.com/javase/9/docs/api/java/util/ArrayList.html
is "autocorrected" (redirected?) to use https instead
https://docs.oracle.com/javase/9/docs/api/java/util/ArrayList.html
which might possibly be related.

Demo:

 $ (for file in JavadocLinkBug.java Makefile; do cat $file; echo ---; done; make clean 9; /usr/bin/google-chrome --incognito --user-data-dir=/tmp/chrome-view-url.gtWVr7Vd7Z --allow-file-access --allow-file-access-from-files --no-first-run file://${PWD}/JavadocLinkBug.html)
public abstract class JavadocLinkBug implements java.util.List {}
---
JDK9 = ~/jdk/jdk9
JDK10 = ~/jdk/jdk10

9:
$(JDK9)/bin/javadoc -link http://docs.oracle.com/javase/9/docs/api/ JavadocLinkBug.java
10:
$(JDK10)/bin/javadoc -link http://docs.oracle.com/javase/9/docs/api/ JavadocLinkBug.java
9-https:
$(JDK9)/bin/ javadoc -link https://docs.oracle.com/javase/9/docs/api/ JavadocLinkBug.java
10-https:
$(JDK10)/bin/javadoc -link https://docs.oracle.com/javase/9/docs/api/ JavadocLinkBug.java

clean:
rm -rf *.html *.js *.css *.zip resources/ jquery/ package-list

.PHONY: 9 10 9-https 10-https clean
---
rm -rf *.html *.js *.css *.zip resources/ jquery/ package-list
~/jdk/jdk9/bin/javadoc -link http://docs.oracle.com/javase/9/docs/api/ JavadocLinkBug.java
Loading source file JavadocLinkBug.java...
Constructing Javadoc information...
Standard Doclet version 9.0.1
Building tree for all the packages and classes...
....