maven-debian-helper=2.0~exp2 rebuild

[Chris West <solo-debian-java@goeswhere.com>]

I did a rebuild of a bunch of packages with maven-debian-helper 2.0~exp2
installed, to see what would break.

The resultant build logs are in https://rbuild.fau.xxx/2015-11-25-mdh-2-2/ ,
and the failures are sorted in the sorted/ subdirectory.  Summary:

38 install-plugin-missing
10 other-missing-plugins
 8 antrun-missing (plugin)
 6 other-compile-failure
 5 other-missing-artifacts
 5 compiler-api-missing
 4 multimodule-project-dir
 3 test-failures
 3 scm-publish-plugin
 3 maven2-settings-debian
 3 builder-failure
 2 invalid-plugin-descriptor

Missing plugins could be one of two things:
 1) I believe maven-debian-helper Requires maven2 Recommends
      maven-install-plugin, which the builders may previously have
      been installing, and this round has not been?  That is, the
      packages were possibly broken anyway, and it just happens that
      this build has caught them.
 2) It is believed that maven3 requires some plugins present, even
      if they're not used during the build, whereas maven 2 would not.

Excluding plugins and probably-unrelated-FTBFS, we're left with:

maven2-settings-debian, which is probably a bug in these packages, e.g.
https://sources.debian.net/src/spatial4j/0.3-1/debian/rules/#L10

    dh_auto_configure
     mh_patchpoms -plibspatial4j-java --debian-build --keep-pom-version
      --maven-repo=/spatial4j-0.3/debian/maven-repo
     mvn install:install-file -s/etc/maven2/settings-debian.xml
      -Dmaven.repo.local=`pwd`/debian/maven-repo
      -Dfile=/usr/share/java/jts.jar -DgroupId=com.vividsolutions
      -DartifactId=jts -Dversion=fake -Dpackaging=jar
    [ERROR] Error executing Maven.
    [ERROR] The specified user settings file does not exist:
      /etc/maven2/settings-debian.xml

multimodule-project-dir, which I don't get at all but causes later failures:

    dh_testdir
     mvn-debian package
      -Dmaven.multiModuleProjectDirectory system property is not set.
          Check $M2_HOME environment variable and mvn script match.
     touch build-stamp
     debian/rules binary

i.e. somewhere between 7 and 20 packages, if some maven plugins are
added to maven-debian-helper's Depends.