gradle-debian-helper relies on an invalid java api directory

[Tiago Stürmer Daitx]

gradle-debian-helper should:
1) declare the binary package gradle-debian-helper as dependend upon
default-jdk-doc;
2) use the directory file:///usr/share/doc/default-jdk-doc/api in
DebianHelperPlugin.java instead of the current default-jdk one.

The reason for this change is that until openjdk-9 the javadoc binary
would ignore invalid javadoc links and at most throw out a warning, but
since openjdk-10 this behavior changed to an error which causes packages
that calls the javadoc binary to FTBFS whenever an invalid, nonexistent,
or unreacheable link is given.

In gradle-debian-helper the file
gradle-helper-plugin/src/main/java/org/debian/gradle/DebianHelperPlugin.java
currently sets the first javadoc link to
file:///usr/share/doc/default-jdk/api

First, this seems to indicates that the plugin expects that the default-jdk
package will be installed when it's used, but this is not reflected upon
its 'Depends:' (or 'Recommends:').

Second, even if the default-jdk is installed this is problematic because that
directory is actually a relative link to
../openjdk-X-doc/api
which in turn belongs to an openjdk-X-doc package - such package is not
installed by the default-jdk package. Instead of looking for a default-jdk
directory I proposed that it should instead look for a default-jdk-doc
directory as the api link because the default-jdk-doc package does depends
on an openjdk-X-doc package.

This change shouldn't cause much problem for any packages currently
building with the default-jdk set to openjdk-9 (or 8), since if
/usr/share/doc/default-jdk-doc does not exist then the default-jdk-doc
was not installed anyway and the original link to
/usr/share/doc/default-jdk/api would be invalid anyway and these openjdk
versions ignore that.

Without the proposed changes packages would FTBFS unless both default-jdk
and default-jdk-doc are installed after the default-jdk moves to
openjdk-10 (or 11). Also, packages that depend upon default-jdk-headless
would FTBFS unless they moved to depend upon default-jdk.

[Tiago Stürmer Daitx (tdaitx)]

Please consider the attached debdiff for fixing this bug.

[Launchpad Janitor (janitor)]

This bug was fixed in the package gradle-debian-helper - 1.6ubuntu1

---------------
gradle-debian-helper (1.6ubuntu1) bionic; urgency=medium

  * Replace javadoc link with default-jdk-doc directory instead of
    default-jdk. LP: #1765883.
  * debian/control: add runtime dependency to default-jdk-doc.

 -- Tiago Stürmer Daitx <email address hidden> Sat, 21 Apr 2018 01:26:08 +0000

[Steve Langasek (vorlon)]

As I understand it, this is fixed in groovy 2.4.15-1ubuntu1.

groovy (2.4.15-1ubuntu1) bionic; urgency=medium

  * Replace HTTP URLs with local files: LP: #1765885.
    - debian/control: build depends on -doc packages so javadoc can
      properly link the apis.
    - debian/patches/10_use_local_docs.patch, debian/control: include
      javadoc apis locally as invalid, unreacheable, or nonexistent
      links cause the build to faild with openjdk-10.