  We prove a multivariate functional version of de Jong's CLT (1990) yielding
that, given a sequence of vectors of Hoeffding-degenerate U-statistics, the
corresponding empirical processes on $[0,1]$ weakly converge in the Skorohod
space as soon as their fourth cumulants in $t=1$ vanish asymptotically and a
certain strengthening of the Lindeberg-type condition is verified. As an
application, we lift to the functional level the `universality of Wiener chaos'
phenomenon first observed in Nourdin, Peccati and Reinert (2010).
