[MWRAPPER-144] Warnings should be printed to stderr not stdout

[jira-importer]

Jakub Bochenski opened MWRAPPER-144 and commented

E.g. this one

Warning: JAVA_HOME environment variable is not set.

This prevents one from using wrapper in scripts:

$ repo=$(./mvnw help:evaluate -Dexpression=settings.localRepository -q -DforceStdout)
$ echo $repo
Warning: JAVA_HOME environment variable is not set. /home/jakub/.m2/repository

Vs calling maven directly

$ repo=$(mvn help:evaluate -Dexpression=settings.localRepository -q -DforceStdout)
$ echo $repo
/home/jakub/.m2/repository

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Issue Links:

• MWRAPPER-113 Error and warning output goes to standard output and intermingles with Maven output
  ("duplicates")