The following URL http://jmockit.org/tutorial/StateBasedTesting.html#proceed it says:

Although not shown here, a call to proceed() can be also be done inside a "$init(Invocation inv, ...)"
mock method, to execute the real implementation of a mocked constructor. Additionally, for
mocked methods/constructors having parameters, we can replace the argument values passed to
the real implementation by passing the replacement values in a proceed(, , ...) call.

When I actually try it, I get:

java.lang.UnsupportedOperationException: Cannot replace arguments when proceeding into constructor