[midPoint] Security Violation with Custom Attribute

[Brad Firestone]

Hi, I'm just getting started with my midPoint configuration.  I have 
setup an OpenLDAP resource that has custom attributes in a custom object 
class.  This resource should not ever be modified, so I have removed all 
inbound settings, since I only want information to go out to this resource.

When I try to project a midPoint user to this resource, I get the 
following error:

Security violation during processing shadow shadow: null (OID:null): 
Attempt to add shadow with non-createable attribute 
{http://midpoint.evolveum.com/xml/ns/public/resource/instance-3}gnUniqueId

The attribute gnUniqueID exists in a custom schema XSD file and it does 
display under the Extension section of the User in the GUI.  Here's the 
related section from the XSD file:

<xsd:element name="gnUniqueID" type="xsd:string" minOccurs="0" 
maxOccurs="1">
<xsd:annotation>
<xsd:appinfo>
<a:indexed>true</a:indexed>
<a:displayName>GN-UniqueID</a:displayName>
<a:displayOrder>120</a:displayOrder>
</xsd:appinfo>
</xsd:annotation>
</xsd:element>

Here is the attribute section of the Resource XML file:

<attribute>
<ref>ri:gnUniqueId</ref>
<displayName>GN Unique ID</displayName>
<limitations>
<access>
<read>true</read>
<add>false</add>
<modify>true</modify>
</access>
</limitations>
<outbound>
<source>
<path>$user/extension/gnUniqueID</path>
</source>
</outbound>
<matchingRule>mr:stringIgnoreCase</matchingRule>
</attribute>

I'll be happy to send additional config information, or the complete 
error file, if that would be helpful.  Thank you for any suggestions on 
how to resolve this error!
Brad