Description

This error appears when trying to use attributes on "extension" inside of an extensionPoint tag: org.apache.taglibs.standard.tag.common.core.NullAttributeException: The "url" attribute illegally evaluated to "null" or "" in <import>

The tag is set up properly like so:

<openmrs:extensionPoint pointId="org.openmrs.module.htmlformentry.edit" type="html">
   <openmrs:portlet url="${extension.portletUrl}" moduleId="${extension.moduleId}"/>
   ...
</openmrs:extensionPoint>

See the thread started by Joao on the developers mailing list here: http://n2.nabble.com/Defining-Portlet-Extensions-points-for-modules-td3073276.html