Java connector passes null as the settlement account id on the setupAccount action

[georgeroman]

While integrating the Hyperledger Iroha settlement engine with the Java connector, I've noticed that the Java connector passes null as the settlement account identifier when setting up an account with the settlement engine (here is the spec for this action). This is not compliant with the specification and it makes certain settlement engines (ilp-iroha-settlement, ethereum-engine) unusable (these settlement engines perform the step of exchanging ledger identifiers (via the connector's messaging endpoint) in the setup account action but since the connector passes null as the settlement account identifier, the messaging endpoint is not available during this action and the exchange of ledger identifiers fails).