solution: optionally provide utxo for bitcoin balance request

build.gradle

@@ -57,7 +57,7 @@ configurations {
 }
 
 dependencies {
-    implementation "io.emeraldpay:emerald-api:0.7.1"
+    implementation "io.emeraldpay:emerald-api:0.8.0"
 
     implementation "io.grpc:grpc-protobuf:${grpcVersion}"
     implementation "io.grpc:grpc-stub:${grpcVersion}"

src/main/kotlin/io/emeraldpay/dshackle/rpc/TrackBitcoinAddress.kt

@@ -64,22 +64,41 @@ class TrackBitcoinAddress(
         }
     }
 
-    fun requestBalances(chain: Chain, api: BitcoinMultistream, addresses: List<String>): Flux<AddressBalance> {
+    fun requestBalances(chain: Chain, api: BitcoinMultistream, addresses: List<String>, includeUtxo: Boolean): Flux<AddressBalance> {
         return Flux.fromIterable(addresses)
                 .map { Address(chain, it) }
                 .flatMap { address ->
-                    api.getReader()
-                            .listUnspent(address.bitcoinAddress)
-                            .map { unspents ->
-                                getTotal(address, unspents)
-                            }
-                            .onErrorResume { t ->
-                                log.error("Failed to get unspent", t)
-                                Mono.empty()
-                            }
+                    balanceForAddress(api, address, includeUtxo)
                 }
     }
 
+    fun balanceForAddress(api: BitcoinMultistream, address: Address, includeUtxo: Boolean): Mono<AddressBalance> {
+        return api.getReader()
+                .listUnspent(address.bitcoinAddress)
+                .map { unspent ->
+                    totalUnspent(address, includeUtxo, unspent)
+                }
+                .onErrorResume { t ->
+                    log.error("Failed to get unspent", t)
+                    Mono.empty()
+                }
+    }
+
+    fun totalUnspent(address: Address, includeUtxo: Boolean, unspent: List<SimpleUnspent>): AddressBalance {
+        return if (unspent.isEmpty()) {
+            AddressBalance(address, BigInteger.ZERO)
+        } else {
+            unspent.map {
+                AddressBalance(
+                        address,
+                        BigInteger.valueOf(it.value),
+                        if (includeUtxo) listOf(BalanceUtxo(it.txid, it.vout, it.value))
+                        else emptyList()
+                )
+            }.reduce { a, b -> a.plus(b) }
+        }
+    }
+
     override fun getBalance(request: BlockchainOuterClass.BalanceRequest): Flux<BlockchainOuterClass.AddressBalance> {
         val chain = Chain.byId(request.asset.chainValue)
         val upstream = multistreamHolder.getUpstream(chain)?.cast(BitcoinMultistream::class.java)
@@ -88,19 +107,10 @@ class TrackBitcoinAddress(
         if (addresses.isEmpty()) {
             return Flux.empty()
         }
-        return requestBalances(chain, upstream, addresses)
+        return requestBalances(chain, upstream, addresses, request.includeUtxo)
                 .map(this@TrackBitcoinAddress::buildResponse)
     }
 
-    fun getTotal(address: Address, unspents: List<SimpleUnspent>): AddressBalance {
-        val total = if (unspents.isEmpty()) {
-            0L
-        } else {
-            unspents.map { it.value }.reduce(Long::plus)
-        }
-        return AddressBalance(address, BigInteger.valueOf(total))
-    }
-
 
     override fun subscribe(request: BlockchainOuterClass.BalanceRequest): Flux<BlockchainOuterClass.AddressBalance> {
         val chain = Chain.byId(request.asset.chainValue)
@@ -110,10 +120,10 @@ class TrackBitcoinAddress(
         if (addresses.isEmpty()) {
             return Flux.empty()
         }
-        val initial = requestBalances(chain, upstream, addresses)
+        val initial = requestBalances(chain, upstream, addresses, request.includeUtxo)
         val following = upstream.getHead().getFlux()
                 .flatMap { block ->
-                    requestBalances(chain, upstream, addresses)
+                    requestBalances(chain, upstream, addresses, request.includeUtxo)
                 }
         val last = HashMap<Address, BigInteger>()
         val result = Flux.merge(initial, following)
@@ -134,15 +144,26 @@ class TrackBitcoinAddress(
                         .setChainValue(address.address.chain.id)
                         .setCode("BTC"))
                 .setAddress(Common.SingleAddress.newBuilder().setAddress(address.address.address))
+                .addAllUtxo(
+                        address.utxo.map { utxo ->
+                            BlockchainOuterClass.Utxo.newBuilder()
+                                    .setBalance(utxo.value.toString())
+                                    .setIndex(utxo.vout.toLong())
+                                    .setTxId(utxo.txid)
+                                    .build()
+                        }
+                )
                 .build()
     }
 
-    open class AddressBalance(val address: Address, var balance: BigInteger = BigInteger.ZERO) {
+    open class AddressBalance(val address: Address, var balance: BigInteger = BigInteger.ZERO, var utxo: List<BalanceUtxo> = emptyList()) {
         constructor(chain: Chain, address: String, balance: BigInteger) : this(Address(chain, address), balance)
 
-        fun plus(other: AddressBalance) = AddressBalance(address, balance + other.balance)
+        fun plus(other: AddressBalance) = AddressBalance(address, balance + other.balance, utxo.plus(other.utxo))
     }
 
+    open class BalanceUtxo(val txid: String, val vout: Int, val value: Long)
+
     class Address(val chain: Chain, val address: String) {
         val network = if (chain == Chain.BITCOIN) {
             MainNetParams()

src/test/groovy/io/emeraldpay/dshackle/rpc/TrackBitcoinAddressSpec.groovy

@@ -53,27 +53,49 @@ class TrackBitcoinAddressSpec extends Specification {
                 Chain.BITCOIN, "1K7xkspJg7DDKNwzXgoRSDCUxiFsRegsSK"
         )
         when:
-        def total = track.getTotal(address, unspents)
+        def total = track.totalUnspent(address, false, unspents)
 
         then:
         total.balance == 100
+        total.utxo.isEmpty()
     }
 
     def "Correct sum for few"() {
         setup:
         def unspents = [
                 new SimpleUnspent("f14b222e652c58d11435fa9172ddea000c6f5e20e6b715eb940fc28d1c4adeef", 0, 100L, 123L),
-                new SimpleUnspent("f14b222e652c58d11435fa9172ddea000c6f5e20e6b715eb940fc28d1c4adeef", 0, 123L, 123L),
+                new SimpleUnspent("17d1c4adf14b222e652c58d11435fa9ee2ddea000c6f5e20e6b715eb940fc28f", 0, 123L, 123L),
         ]
         TrackBitcoinAddress track = new TrackBitcoinAddress(Stub(MultistreamHolder))
         def address = new TrackBitcoinAddress.Address(
                 Chain.BITCOIN, "1K7xkspJg7DDKNwzXgoRSDCUxiFsRegsSK"
         )
         when:
-        def total = track.getTotal(address, unspents)
+        def total = track.totalUnspent(address, false, unspents)
 
         then:
         total.balance == 223
+        total.utxo.isEmpty()
+    }
+
+    def "Correct sum for few with utxo"() {
+        setup:
+        def unspents = [
+                new SimpleUnspent("f14b222e652c58d11435fa9172ddea000c6f5e20e6b715eb940fc28d1c4adeef", 0, 100L, 123L),
+                new SimpleUnspent("17d1c4adf14b222e652c58d11435fa9ee2ddea000c6f5e20e6b715eb940fc28f", 0, 123L, 123L),
+        ]
+        TrackBitcoinAddress track = new TrackBitcoinAddress(Stub(MultistreamHolder))
+        def address = new TrackBitcoinAddress.Address(
+                Chain.BITCOIN, "1K7xkspJg7DDKNwzXgoRSDCUxiFsRegsSK"
+        )
+        when:
+        def total = track.totalUnspent(address, true, unspents)
+
+        then:
+        total.balance == 223
+        total.utxo.size() == 2
+        total.utxo[0].txid == "f14b222e652c58d11435fa9172ddea000c6f5e20e6b715eb940fc28d1c4adeef"
+        total.utxo[1].txid == "17d1c4adf14b222e652c58d11435fa9ee2ddea000c6f5e20e6b715eb940fc28f"
     }
 
     def "One address for single provided"() {