Solution (untested):

Step 1:

package Friendly::Hint;
use base 'Exporter';
use Carp qw(croak);

our @EXPORT = qw(null);

sub null {
  croak("ERROR: Java programmer detected.");
}

1;
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Step 2:

echo "PERL5OPT=-MFriendly::Hint" > /etc/profile.d/perl.sh
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