I'm new to Qiskit.
I am trying to construct a gate from HamiltonianGate(), available on Qiskit. The Hamiltonian in question is:
$$H = - \pi\delta(Z_1 - Z_2)
       + 2\pi J ~ \mathbf{I}_1 \cdot \mathbf{I}_2$$
where $\mathbf{I}_1$ and $\mathbf{I}_2$ are Pauli vectors, each for system 1 and system 2, respectively. 

Although I was able to do so by using `HamiltonianGate()`, when I try to see my circuit, I end up getting something like this:


[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/jcTcr.png

I was hoping to find explicit gate decomposition of my unitary from `HamiltonianGate()`, but I'm unable to find a way to do so. 

Please do let me know how I can proceed from here and obtain the explicit gate decompositions. If this is, for some reason, not possible, then please do let me know why it is so. Also, if given this scenario, any help in simulating the unitary associated with the above Hamiltonian via elementary gates would be very much appreciated!