FULL PRODUCT VERSION :
java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Ubuntu Linux 13.10, x86_64

A DESCRIPTION OF THE PROBLEM :
First noticed with gradle while building the javadoc for one of my projects. From the debug file:

----
11:59:45.949 [INFO] [org.gradle.process.internal.DefaultExecHandle] Starting process 'command '/opt/sunjdk/1.8/jdk1.8.0/bin/javadoc''. Working directory: /home/fge/src/perso/largetext Command: /opt/sunjdk/1.8/jdk1.8.0/bin/javadoc @/home/fge/src/perso/largetext/build/tmp/javadoc/javadoc.options
----

The javadoc.options file contains the following:

----
-classpath '/home/fge/src/perso/largetext/build/classes/main:/home/fge/src/perso/largetext/build/resources/main:/home/fge/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/16.0.1/5fa98cd1a63c99a44dd8d3b77e4762b066a5d0c5/guava-16.0.1.jar:/home/fge/.gradle/caches/modules-2/files-2.1/com.google.code.findbugs/jsr305/2.0.1/516c03b21d50a644d538de0f0369c620989cd8f0/jsr305-2.0.1.jar'
-d '/home/fge/src/perso/largetext/build/docs/javadoc'
-doctitle 'largetext 0.1-SNAPSHOT API'
-link 'http://docs.oracle.com/javase/7/docs/api'
-link 'http://jsr-305.googlecode.com/svn/trunk/javadoc'
-link 'http://docs.guava-libraries.googlecode.com/git-history/v16.0.1/javadoc'
-quiet
-overview 'src/main/java/overview.html'
-windowtitle 'largetext 0.1-SNAPSHOT API'
'/home/fge/src/perso/largetext/src/main/java/com/github/fge/largetext/LargeTextFactory.java'
[ etc etc]
---

But the javadoc process does not find the links. From the debug file again:

----
11:59:47.959 [ERROR] [system.err] javadoc: warning - Error fetching URL: http://docs.oracle.com/javase/7/docs/api
11:59:48.217 [ERROR] [system.err] javadoc: warning - Error fetching URL: http://jsr-305.googlecode.com/svn/trunk/javadoc
11:59:48.472 [ERROR] [system.err] javadoc: warning - Error fetching URL: http://docs.guava-libraries.googlecode.com/git-history/v16.0.1/javadoc
----

The workaround is to add trailing slashes to the links, ie:

http://docs.oracle.com/javase/7/docs/api/

instead of:

http://docs.oracle.com/javase/7/docs/api

Java 7's javadoc didn't have this problem.

REGRESSION. Last worked in version 7u51

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Write an options file for the javadoc tool; add in it:

----
-link 'http://docs.oracle.com/javase/7/docs/api'
----

and all other relevant options. Launch the javadoc tool with "javadoc @path/to/optionfile".

See that the command generates a warning on stderr:

warning - Error fetching URL: http://docs.oracle.com/javase/7/docs/api


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The javadoc is generated properly, with external links
ACTUAL -
The javadoc tool is unable to find the links

ERROR MESSAGES/STACK TRACES THAT OCCUR :
warning - Error fetching URL: http://docs.oracle.com/javase/7/docs/api
warning - Error fetching URL: http://jsr-305.googlecode.com/svn/trunk/javadoc
warning - Error fetching URL: http://docs.guava-libraries.googlecode.com/git-history/v16.0.1/javadoc


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
not relevant here
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Add a trailing / to each link option, ie:

-link http://docs.oracle.com/javase/7/docs/api/

instead of:

-link http://docs.oracle.com/javase/7/docs/api