  One of the defining features of spontaneously broken time-reversal symmetry
(BTRS) is the existence of domain walls, the detection of which would be strong
evidence for such systems. There is keen interest in BTRS currently, in part,
due to recent muon spin rotation experiments, which have pointed towards
$\textrm{Ba}_{1-x}\textrm{K}_x\textrm{Fe}_2\textrm{As}_2$ exhibiting a
remarkable case of $s$-wave superconductivity with spontaneously broken
time-reversal symmetry. A key question, however, is how to differentiate
between the different theoretical models which describe such a state. Two
particularly popular choices of model are $s+is$ and $s+id$ superconducting
states. In this paper, we obtain solutions for domain walls in $s+is$ and
$s+id$ systems, including the effects of lattice anisotropies. We show that, in
general, both models exhibit spontaneous magnetic field, that extend along the
entire length of the domain wall. We demonstrate the qualitative difference
between the magnetic signatures of $s+is$ and $s+id$ domain walls and propose a
procedure to extract the superconducting pairing symmetry from the
magnetic-field response of domain walls.
