Why $rsyslog::params::rsyslog_d gets purged?

On Debian (squeeze) when installing other packages (like postfix) some of them add files to /etc/rsyslog.d/

In particular I can't see how to add postfix include to the mix of this module without coupling it with others or coding a specific hack on template.

Postfix include (/etc/rsyslog.d/postfix.conf) looks like:
~~~
# Create an additional socket in postfix's chroot in order not to break
# mail logging when rsyslog is restarted.  If the directory is missing,
# rsyslog will silently skip creating the socket.
$AddUnixListenSocket /var/spool/postfix/dev/log
~~~
Update manifests/config.pp
Update manifests/config.pp
Update manifests/params.pp
Merge pull request #19 from jpknoll/patch-4

Patch 4
remove trailing slash
fixes #17
whitespace consistency
fixes #18
Version 2.0.0
Update README.md

fix a typoed default
Merge pull request #22 from rjw1/patch-1

Update README.md
add module summary
refactor tests to reduce duplication
Rename server.conf.erb to server-default.conf.erb and create _default partial templates

Split out server template into two parts:
server/_default-{header,footer}.conf.erb which hold unchaning values
server-default.conf.erb which contains commonly modified values, and
imports _default.conf.erb
Change default template to server-default.conf.erb
Update tests to check content of server.conf
Add server-hostname template and tests
Update documentation to explain default behaviour of rsyslog::server and suggest alternative
Add `custom_params` to `rsyslog::client` for custom templates

When doing lookups in templates, variables that are not explicitly
scoped with `scope.lookupvar()` must be in the scope of the `template()`
function call. `rsyslog::client` allows custom templates to be called,
but doesn't allow custom parameters to be passed for the alterate
template to use.

This pull request adds a `custom_params` parameter so a hash of extra
parameters may be passed for the custom template to access without
explicit scoping knowledge.
Rename $InputFilePollingInterval to $InputFilePollInterval
Merge pull request #26 from johanek/imfile

Rename $InputFilePollingInterval to $InputFilePollInterval