unable to set additional groups

[Fabrizio Magni]

Hello,
when I start tomcat using monit I cannot see the "additional groups" set.
If I launch the process manually the additional groups are there.

Example:

monit --version
This is Monit version 5.11
Copyright (C) 2001-2014 Tildeslash Ltd. All Rights Reserved.

Monit configuration for the tomcat resource:

check process tomcat with pidfile /opt/tomcat/logs/tomcat.pid
    start program = "/opt/tomcat/bin/startup.sh"  as uid tomcat7 and 
gid tomcat7 with timeout 60 seconds
    stop  program = "/bin/bash -c 'kill -s SIGKILL `cat 
/opt/tomcat/logs/tomcat.pid`'" as uid root and gid root with timeout 60 
seconds

monit is running as root.

The process started by monit:
tomcat7  24855     1  8 16:41 ?        00:03:48 
/opt/jrockit-1.6.0//bin/java 
-Djava.util.logging.config.file=/opt/tomcat/conf/logging.properties

cat /proc/24855/status
Name:   java
State:  S (sleeping)
Tgid:   24855
Pid:    24855
PPid:   1
TracerPid:      0
Uid:    108     108     108     108
Gid:    115     115     115     115
FDSize: 256
Groups: 0

uid 108 = tomcat7 (user)
gid 115 = tomcat7  (group)

but tomcat7 is in www-data group as well (gid 37). This is not set when 
tomcat start using monit (as in proc output above).

Any idea?

Thanks
Fabrizio