Struggling with Travis CI and Maven 3.3

I struggled with fixing Travis CI for my "labs" code. The main problem is lack of support for Maven 3.3; my POM enforcer requires it. Eventually I got something working with help from the Internet, though I'm not happy with it. It manually downloads and uses maven 3.3:

sudo: false
language: java
jdk:
  - oraclejdk8
# TODO: Gross until Travis support setting maven version or upgrades to 3.3
before_install:
  - wget http://apache.claz.org/maven/maven-3/3.3.3/binaries/apache-maven-3.3.3-bin.tar.gz
  - tar zxvf apache-maven-3.3.3-bin.tar.gz
  - chmod +x apache-maven-3.3.3/bin/mvn
  - export M2_HOME=$PWD/apache-maven-3.3.3
  - export PATH=$PWD/apache-maven-3.3.3/bin:${PATH}
  - hash -r
before_script:
  - export M2_HOME=$PWD/apache-maven-3.3.3
  - export PATH=$PWD/apache-maven-3.3.3/bin:${PATH}
  - hash -r
script: mvn verify -Dgpg.skip=true

Bonus

On another project using Travis CI I ran afoul of the 10,000 line limit for displaying build output in the web UI. Workaround, add this to the build_install section:

  - echo 'MAVEN_OPTS="-Dorg.slf4j.simpleLogger.defaultLogLevel=warn"' >~/.mavenrc

If you're using maven 3.3 or better, Karl Heinz Marbaise has a better approach with .mvn/jvm.config.