According to https://docs.travis-ci.com/user/languages/java#overview when using “language: java” Maven and Gradle come pre-installed and available to use. Only Ant should be manually installed.
It appears that Maven is not available when executing on ARM64 VM.
mvn is not available in ARM64 builds: https://travis-ci.org/github/martin-g/activemq-artemis/jobs/675206911
The same build starts fine on AMD64: https://travis-ci.org/github/martin-g/activemq-artemis/jobs/675206910