The asset node asks the LA which network accounts it already associates with
finId on (organizationId, assetId) — e.g. wallets whitelisted directly on the
adapter or its external system. The LA answers with the full array. Nothing is
created and no challenge is ever issued. An empty array is a successful, empty
result.

Return production wallets only. The array must contain the investor's real
accounts on this asset — the ones the adapter actually holds or has whitelisted for
that investor. Never return test, placeholder or freshly generated wallets. Every
returned wallet is bound on the router as an onboarded network account for the
investor on (organizationId, assetId), replacing whatever the router previously
held for that pair, and will be accepted on the investor's execution legs. Return an
empty array if the adapter holds none.

Two response shapes, both 202:

• isCompleted: true — the result is inline in accounts.
• isCompleted: false — cid is returned and the result arrives on
  GET /operations/status/{cid} (or the callback, per operationResponseStrategy)
  as networkAccountOperation.accounts.

A ledger adapter that does not support lookup answers 501; the asset node fails the
operation with a terminal business error (7352).