We have a simple persistent component called RosterEmbargo tied to an MSSQL 2012 view. For compatibility with some old code, it uses a compound PK - an integer field (seasonID) and a guid field (teamID).
We can load an instance of this component but we cannot save it within a transaction without getting this error - note the change from the seasonID int (1) to 1.0.
Code to reproduce this:
Full stack trace:
Windows 10 / Java 1.8.0_91, MSSQL 2012, Microsoft JDBC drivers (same issue with jTDS)