Adds a ShareAccountKeyFlow.

workflows/src/main/kotlin/com/r3/corda/lib/accounts/workflows/flows/ShareAccountKeyFlows.kt

@@ -0,0 +1,68 @@
+package com.r3.corda.lib.accounts.workflows.flows
+
+import co.paralleluniverse.fibers.Suspendable
+import com.r3.corda.lib.accounts.contracts.states.AccountInfo
+import com.r3.corda.lib.accounts.workflows.accountService
+import com.r3.corda.lib.accounts.workflows.internal.flows.AccountSearchStatus
+import net.corda.core.flows.*
+import net.corda.core.utilities.unwrap
+import java.security.PublicKey
+import java.util.*
+
+/**
+ * This flow can be used to share a [PublicKey]-[AccountInfo] mapping with another host.
+ * Just like the use of [RequestKeyForAccountFlow] handle such mappings from remote accounts,
+ * this flow allows the remote host to handle the mapping for the provided key.
+ *
+ * @property accountKey the [PublicKey] to share.
+ * @property hostSession session to share the [accountKey] with.
+ */
+class ShareAccountKeyFlow(private val accountKey: PublicKey,
+                          private val hostSession: FlowSession)
+    : FlowLogic<Unit>()
+{
+    @Suspendable
+    override fun call() {
+        if (serviceHub.myInfo.legalIdentities.contains(hostSession.counterparty)) {
+            return
+        }
+
+        val accountInfo = accountService.accountInfo(accountKey)?.state?.data
+                ?: throw FlowException("Cannot find any account for the given key on this node.")
+
+        val accountSearchStatus = hostSession.sendAndReceive<AccountSearchStatus>(accountInfo.identifier.id).unwrap { it }
+        if (accountSearchStatus == AccountSearchStatus.NOT_FOUND) {
+            // In order to bind the provided key to an account, the latter must be known by the receiver host.
+            accountService.shareAccountInfoWithParty(accountInfo.identifier.id, hostSession.counterparty)
+        }
+
+        hostSession.send(accountKey)
+    }
+}
+
+/**
+ * Responder flow for [ShareAccountKeyFlow].
+ */
+class ShareAccountKeyHandlerFlow(private val providerSession: FlowSession)
+    : FlowLogic<Unit>()
+{
+    @Suspendable
+    override fun call() {
+        if (serviceHub.myInfo.legalIdentities.contains(providerSession.counterparty)) {
+            return
+        }
+
+        val accountUUID = providerSession.receive<UUID>().unwrap { it }
+
+        val existingAccountInfo = accountService.accountInfo(accountUUID)
+        if (existingAccountInfo == null) {
+            providerSession.send(AccountSearchStatus.NOT_FOUND)
+        } else {
+            providerSession.send(AccountSearchStatus.FOUND)
+        }
+
+        val accountKey = providerSession.receive<PublicKey>().unwrap { it }
+
+        serviceHub.identityService.registerKey(accountKey, providerSession.counterparty, accountUUID)
+    }
+}