  The electron band around $M$ point in (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$ compound
-- completely lifted above the Fermi level for $x > 0.7$ and hence has no Fermi
Surface (FS) -- can still form an isotropic s-wave gap ($\Delta_e$) and it is
the main pairing resource generating an s-wave gap ($\Delta_h$) with an
opposite sign on the hole pocket around $\Gamma$ point. The electron band
developing the SC order parameter $\Delta_e$ but having no FS displays a {\it
shadow gap} feature which will be easily detected by various experimental
probes such as angle-resolved photoemission spectroscopy (ARPES) and scanning
tunneling microscope (STM). Finally, the formation of the nodal gap
$\Delta_{nodal}$ with $A_{1g}$ symmetry on the other hole pocket with a larger
FS is stabilized due to the balance of the interband pairing interactions from
the main hole band gap $\Delta_h=+\Delta$ and the hidden electron band gap
$\Delta_e = -\Delta$.
