I hope someone from the "SQL Developer Exchange" team reads this - oddly enough there's no admin contact mentioned on that website...
So I tried to share some of my custom reports, but when I try to create one by uploading an XML file saved from SqlDev 4.0 (and filling in all other fields, of course), the following error is thrown:
ORA-01400: cannot insert NULL into ("DBTOOLS"."XML_REPORT"."CREATED_BY")
Unable to process row of table XML_REPORT.
Could this be the reason why the most recent public report is already 3 years old?