Moves money from one of your wallets to up to 100 destinations, with
the amounts you send. Each destination becomes a leg with its own
status, and names who is paid in one of five ways:

• a payee: payeeId, from an earlier disbursement or
  POST /payees;
• a person: emailAddress and/or mobileNumber, with name if
  they are new to PayKeeper and ssn if you have it;
• a company: organizationName and the contact's emailAddress
  (with name for the contact and ein if you have them);
• a company already on PayKeeper: organizationId;
• a wallet: walletId, one of your own wallets (a holdback into a
  reserve wallet, say), or a payee's wallet.

People and companies are found or created exactly as POST /payees
would, and the leg's payeeId says who they resolved to. The same
person or company named in a later disbursement is the same payee. A
leg to anyone who has not yet claimed their account carries their
onboardingUrl, ready for your own email. A company new to PayKeeper
is paid into a wallet PayKeeper holds for it until it onboards; when
it does, that money and every later payment reach its own wallet.

The wallet must be able to cover the total plus PayKeeper's fee (see
Fees), or nothing is created: ids, rules and the balance are checked
before any payee is found or created, and before any money moves. The
balance that counts is what is left after disbursements you have
already made that are still settling, so two disbursements can never
spend the same money. One disbursement from a wallet is created at a
time; a second sent meanwhile gets 409 wallet_busy, and can simply be
sent again. The legs and the fee are written together or not at all,
and none of them moves until all of them exist. If PayKeeper cannot
confirm the balance with its ledger just then, or cannot finish writing
in time, the answer is a 503 and nothing is created.

If a destination cannot be resolved (a 409 name_mismatch, say),
nothing is created: every destination is checked before any payee is
found or created for another. A request that fails after that, with a
503, pays nobody, but a payee it created on the way stays, and a
retry finds the same payee again.

A leg doesn't post only if the wallet can no longer cover it, or
PayKeeper cancels or rejects it; its failureCode says which, and its
money stays in the source wallet. To pay it again, send a new
disbursement with just that leg, under new externalIds. A leg never
waits for money: if money leaves the wallet after the disbursement was
accepted (a returned deposit, say) and a leg can no longer be covered,
that leg is canceled with failureCode: INSUFFICIENT_FUNDS, so it can
never pay out of money that arrives later.

Every disbursement is sent with an Idempotency-Key. A retry with the
same key and body never pays twice: it gets this disbursement back,
with Idempotent-Replayed: true, even if the first response was lost
after the disbursement was accepted.

The response is the disbursement as accepted, usually PROCESSING.
The payout and disbursement webhooks tell you the outcome, and
GET /disbursements/{disbursementId} is the record.