Finite Class 2 Nilpotent and Heisenberg Groups

We present a structural description of finite nilpotent groups of class at most $2$ using a specified number of subdirect and central products of $2$-generated such groups. As a corollary, we show that all of these groups are isomorphic to a subgroup of a Heisenberg group satisfying certain properties. The motivation for these results is of topological nature as they can be used to give lower bounds to the nilpotently Jordan property of the birational automorphism group of varieties and the homeomorphism group of compact manifolds.