ModeShape/modeshape-tools — pull request #3 by elvisisking (2012-06-04 13:11:11+00:00)
Title: MODE-1479 Exception Adding/Editing Property Definition's Value Constraint In CND Editor

The exception was caused by trying to add to unmodifiable list. Also found that the same issue occurred when adding/editing a property definition's default values so that was fixed as well.