The WPS PagedUnique process will give wrong results if the input layer name exists in two different workspaces.
In GeoServer 2.8.5 the process will fail with a message "Failed to retrieve value for input features
Could not locate TEST_LAYER in catalog."
In GeoServer 2.13.x the proces will succeed with wrong results.
To reproduce with the standard data_dir:
Re-publish the tigeroi layer and name it TEST_LAYER
Re-publish the sf:restricted layer and name it TEST_LAYER
Query the tiger:TEST_LAYER to get all the values of the "NAME" property, the WPS body follows:
GeoServer 2.8.5 will fail, GeoServer 2.13 will return the correct results.
Use the same request and just change the workspace name of the layer
GeoServer 2.8.5 will fail, GeoServer 2.13 will return the previous results (the tiger:TEST_LAYER one)
Note that the sf:TEST_LAYER does not have a "NAME" property.
Windows standalone binary with 2.8.5 and 2.13-master
Linux tomcat with 2.8.5
All GeoServer with the matching WPS plugin