When a process has variable of type java.util.Date, the generated form, if showTime attribute is true, does NOT allow inserting the time part. Then after submitting the Date variable shows all zeros in time part of the datatype.

Looking at java.util.Date definition it claims "The class Date represents a specific instant in time, with millisecond precision.". So it is a valid case that should be allowed.

It does occur in KIE server rendered forms, that is either in REST API directly or when using property forms.renderer.ext in Business Central.