Fix high priority Findbugs warnings
Fix high priority Findbugs warning
Fix high priority Findbugs warning (missing hashCode), Fix bug in equals
Fix high priority Findbugs warning
Fix #1992 Updating data explorer rows with nillable mref and no values results in error
Fix #2042 Using extends gives duplicate attributes in the standardsregistry tree view
Merge pull request #2070 from dennishendriksen/master

Fix high priority Findbugs warnings + bug fixes