Maven build fail: "invalid target release" only in GitLab CI

Grumbunks :

Part of my GitLab CI pipeline uses Maven ( mvn test ). Maven fails to build my test project with the following error:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile (default-testCompile) on project GenericTests: Fatal error compiling: invalid target release: 13 -> [Help 1]

I did some research and apparently setting JAVA_HOME to the location of JDK 13 would work, and it does, but only when I do it by hand locally via SSH.

In my pipeline, even if I export JAVA_HOME right before running mvn test I still get the same error.

script:
     - export JAVA_HOME=/usr/java/jdk-13.0.2
     - mvn test

Why does this work differently between GitLab CI and SSH? Could it have to do with the fact that GitLab CI is a non-interactive shell? What can I do to remedy this?

EDIT: I also tried to add a release tag in pom.xml like so:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <version>3.8.1</version>
  <configuration>
    <release>13</release>
  </configuration>
</plugin>

but this only resulted in another error during build time:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:testCompile (default-testCompile) on project GenericTests: Fatal error compiling: invalid flag: --release -> [Help 1]

Grumbunks :

It turned out to be a mess-up on my part: mvn test was being executed by means of an alias, which was actually sudo mvn test. Hence why the environment variable wasn't being used and why I got Mojo permission denied errors locally when I tried to rerun tests.