“…The approach has also been extended along several directions [10,14,18,24,25,27,28,39], including Hamiltonian BVPs [1], constrained Hamiltonian problems [15], highly-oscillatory problems [2,21,38], and Hamiltonian PDEs [3,13,16,17,21,40]. We also refer to the review paper [20] and to the monograph [19]. The basic idea line integral methods rely on is that the conservation of an invariant can be recast as the vanishing of a corresponding line-integral.…”