node: Address review comments

node/src/main/kotlin/com/r3corda/node/internal/ServerRPCOps.kt

@@ -63,11 +63,17 @@ class ServerRPCOps(
         val builder: TransactionBuilder = TransactionType.General.Builder(null)
         // TODO: Have some way of restricting this to states the caller controls
         try {
-            Cash().generateSpend(builder, req.amount.withoutIssuer(), req.recipient.owningKey,
+            val vaultCashStates = services.vaultService.currentVault.statesOfType<Cash.State>()
             // TODO: Move cash state filtering by issuer down to the contract itself
-                    services.vaultService.currentVault.statesOfType<Cash.State>().filter { it.state.data.amount.token == req.amount.token },
-                    setOf(req.amount.token.issuer.party))
-                    .forEach {
+            val cashStatesOfRightCurrency = vaultCashStates.filter { it.state.data.amount.token == req.amount.token }
+            val keysForSigning = Cash().generateSpend(
+                    tx = builder,
+                    amount = req.amount.withoutIssuer(),
+                    to = req.recipient.owningKey,
+                    assetsStates = cashStatesOfRightCurrency,
+                    onlyFromParties = setOf(req.amount.token.issuer.party)
+            )
+            keysForSigning.forEach {
                 val key = services.keyManagementService.keys[it] ?: throw IllegalStateException("Could not find signing key for ${it.toStringShort()}")
                 builder.signWith(KeyPair(it, key))
             }

node/src/main/kotlin/com/r3corda/node/services/messaging/CordaRPCOps.kt

@@ -97,7 +97,8 @@ interface CordaRPCOps : RPCOps {
     fun verifiedTransactions(): Pair<List<SignedTransaction>, Observable<SignedTransaction>>
 
     /**
-     * Returns a pair of state machine id - recorded transaction hash pairs
+     * Returns a snapshot list of existing state machine id - recorded transaction hash mappings, and a stream of future
+     * such mappings as well.
      */
     @RPCReturnsObservables
     fun stateMachineRecordedTransactionMapping(): Pair<List<StateMachineTransactionMapping>, Observable<StateMachineTransactionMapping>>