  We analyse higher-spin theory with general coupling constant $\eta$ at the
second order, focusing on the gauge non-invariant vertices
$\Upsilon(\omega,\omega)$, $\Upsilon(\Omega,\omega,C)$ and
$\Upsilon(\omega,C)$, that are shown to generate nontrivial currents in the
Fronsdal equations. Explicit expressions for the currents are found in the
frame-like formalism counterpart of the TT gauge worked out in the paper. The
nonlinear higher-spin theory is shown to generate all types of Metsaev's
currents with the coupling constants manifestly expressed via the complex
coupling constant $\eta$ of the higher-spin theory. It is shown that all
currents in the higher-spin theory are conformal in the TT gauge except for
those bilinear in the higher-spin gauge fields $\omega$.
