@InitiatingFlow
@StartableByRPC
class IOUIssueFlow(val state: IOUState) : FlowLogic<SignedTransaction>() {
   @Suspendable
   override fun call(): SignedTransaction {
       val txCommand = Command(
               IOUContract.Commands.Issue(),
               state.participants.map { it.owningKey })
       val builder = TransactionBuilder(serviceHub.networkMapCache.notaryIdentities.first())
               .withItems(
                       StateAndContract(
                               state,
                               IOUContract.IOU_CONTRACT_ID),
                       txCommand)
       builder.verify(serviceHub)
       val others = state.participants - ourIdentity
       return subFlow(
               FinalityFlow(
                       subFlow(
                               CollectSignaturesFlow(
                                       serviceHub.signInitialTransaction(builder),
                                       others.map { initiateFlow(it as Party) }.toSet()))))
   }
}

[WARN ] 16:38:13,655 [Mock network] (FlowStateMachineImpl.kt:127) flow.[49f2ebbd-be62-462d-af87-24f5ae40c7d6].run - Terminated by unexpected exception
java.lang.NullPointerException: null
    at net.corda.node.services.statemachine.FlowStateMachineImpl.suspend(FlowStateMachineImpl.kt:468) ~[corda-node-1.0.0.jar:?]
    at net.corda.node.services.statemachine.FlowStateMachineImpl.sendInternal(FlowStateMachineImpl.kt:332) ~[corda-node-1.0.0.jar:?]
    at net.corda.node.services.statemachine.FlowStateMachineImpl.initiateSession(FlowStateMachineImpl.kt:396) ~[corda-node-1.0.0.jar:?]
    at net.corda.node.services.statemachine.FlowStateMachineImpl.sendAndReceive(FlowStateMachineImpl.kt:200) ~[corda-node-1.0.0.jar:?]
    at net.corda.core.internal.FlowStateMachine$DefaultImpls.sendAndReceive$default(FlowStateMachine.kt:27) ~[corda-core-1.0.0.jar:?]
    at net.corda.node.services.statemachine.FlowSessionImpl.sendAndReceive(FlowSessionImpl.kt:25) ~[corda-node-1.0.0.jar:?]
    at net.corda.core.flows.DataVendingFlow.sendPayloadAndReceiveDataRequest(SendTransactionFlow.kt:70) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.DataVendingFlow.call(SendTransactionFlow.kt:48) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.DataVendingFlow.call(SendTransactionFlow.kt:31) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:212) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.CollectSignatureFlow.call(CollectSignaturesFlow.kt:140) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.CollectSignatureFlow.call(CollectSignaturesFlow.kt:134) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:212) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.CollectSignaturesFlow.call(CollectSignaturesFlow.kt:113) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.CollectSignaturesFlow.call(CollectSignaturesFlow.kt:64) ~[corda-core-1.0.0.jar:?]
    at net.corda.core.flows.FlowLogic.subFlow(FlowLogic.kt:212) ~[corda-core-1.0.0.jar:?]
    at net.corda.training.flow.IOUIssueFlow.call(IOUIssueFlow.kt:39) ~[classes/:?]
    at net.corda.training.flow.IOUIssueFlow.call(IOUIssueFlow.kt:22) ~[classes/:?]
    at net.corda.node.services.statemachine.FlowStateMachineImpl.run(FlowStateMachineImpl.kt:112) [corda-node-1.0.0.jar:?]
    at net.corda.node.services.statemachine.FlowStateMachineImpl.run(FlowStateMachineImpl.kt:40) [corda-node-1.0.0.jar:?]
    at co.paralleluniverse.fibers.Fiber.run1(Fiber.java:1092) [quasar-core-0.7.9-jdk8.jar:0.7.9]
    at co.paralleluniverse.fibers.Fiber.exec(Fiber.java:788) [quasar-core-0.7.9-jdk8.jar:0.7.9]
    at co.paralleluniverse.fibers.RunnableFiberTask.doExec(RunnableFiberTask.java:100) [quasar-core-0.7.9-jdk8.jar:0.7.9]
    at co.paralleluniverse.fibers.RunnableFiberTask.run(RunnableFiberTask.java:91) [quasar-core-0.7.9-jdk8.jar:0.7.9]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_151]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_151]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) [?:1.8.0_151]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) [?:1.8.0_151]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_151]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_151]
    at net.corda.node.utilities.AffinityExecutor$ServiceAffinityExecutor$1$thread$1.run(AffinityExecutor.kt:69) [corda-node-1.0.0.jar:?]
[WARN ] 16:38:13,670 [Mock network] (StateMachineManager.kt:93) flow.[49f2ebbd-be62-462d-af87-24f5ae40c7d6].uncaughtException - Caught exception from flow
java.lang.IllegalStateException: No transaction in context