Using non-empty MAVEN_OPTS (dummy prop) to prevent from merging env vars in child integration test with env vars from (caller) parent process.
The child env var takes the precedence in this fix.
Merging env vars between parent/child processes is performed in maven-shared-utils:
see Commandline#addSystemEnvironment() and see the line
Properties systemEnvVars = CommandLineUtils.getSystemEnvVars().
With this fix we can freely use the MAVEN_OPTS within our integration tests.