MS SQL Server size of NVARCHAR defect

As said here [1], SQL Server allows up to 4000 chars in NVARCHAR type.

The file /continuum-model/src/main/resources/package-mssql.orm should be changed. 8000 should be changed to 4000 inside.

Patch is attached.

[1] http://msdn.microsoft.com/en-us/library/ms186939.aspx