Do not use ~/.m2/settings.xml provided by Travis

[Godin]

In Travis maven-javadoc-plugin:2.10.4 tries to download some artifacts and causes long build times:

...
[INFO] --- maven-javadoc-plugin:2.10.4:jar (attach-javadocs) @ org.jacoco.doc ---
...
[INFO] Downloading from sonatype: https://oss.sonatype.org/content/repositories/releases/org/ow2/asm/asm-commons/6.2.1/asm-commons-6.2.1-javadoc-resources.jar
[INFO] Downloading from sonatype-apache: https://repository.apache.org/releases/org/ow2/asm/asm-commons/6.2.1/asm-commons-6.2.1-javadoc-resources.jar
...
[INFO] JaCoCo :: Documentation ............................ SUCCESS [21:35 min]
...

Repositories sonatype and sonatype-apache are defined by Travis in its ~/.m2/settings.xml and seems that there is an issue with access to these repositoeis from Travis (can't reproduce locally).

---

Attempts to download disappear after upgrade of maven-javadoc-plugin to latest released version 3.0.1.
But I didn't managed to find ticket or corresponding change to understand why.

Also due to changes for MJAVADOC-498 this upgrade causes non fatal error messages

...
[INFO] --- maven-javadoc-plugin:3.0.1:jar (attach-javadocs) @ org.jacoco.doc ---
[ERROR] no module descriptor for org.jacoco:org.jacoco.doc
[ERROR] no module descriptor for org.jacoco:org.jacoco.core
[ERROR] no module descriptor for org.jacoco:org.jacoco.report
[ERROR] no module descriptor for org.jacoco:org.jacoco.agent
[ERROR] no module descriptor for org.jacoco:org.jacoco.agent.rt
[ERROR] no module descriptor for org.jacoco:org.jacoco.ant
[ERROR] no module descriptor for org.jacoco:org.jacoco.cli
[ERROR] no module descriptor for org.jacoco:org.jacoco.examples
[ERROR] no module descriptor for org.jacoco:jacoco-maven-plugin
...
[INFO] JaCoCo :: Documentation ............................ SUCCESS [  4.643 s]
[INFO] JaCoCo :: Distribution ............................. SUCCESS [  1.540 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
...

even when using JDK 8.

---

Since in absence of custom repositories attempts to download also disappear, I propose to simply stop using ~/.m2/settings.xml that is provided by Travis.

[marchof]

Nice that you identified this!