Fix FObjectView overriding any default value of objectClass when data is set.
Fix FObjectView overriding any default value of objectClass when data is set.

Instead just clear objectClass when data is set to null.

foam-framework/foam2,jacksonic/vjlofvhjfgm,foam-framework/foam2,jacksonic/vjlofvhjfgm,foam-framework/foam2,foam-framework/foam2,foam-framework/foam2,jacksonic/vjlofvhjfgm