problem: uses only one Head Subscription for Dshackle Upstream even if multiple are provided

src/main/kotlin/io/emeraldpay/dshackle/upstream/grpc/BitcoinGrpcUpstream.kt

@@ -93,7 +93,7 @@ class BitcoinGrpcUpstream(
             }
     }
     private val upstreamStatus = GrpcUpstreamStatus()
-    private val grpcHead = GrpcHead(chain, this, blockConverter, reloadBlock)
+    private val grpcHead = GrpcHead(chain, this, remote, blockConverter, reloadBlock)
     var timeout = Defaults.timeout
     private var capabilities: Set<Capability> = emptySet()
 
@@ -126,15 +126,13 @@ class BitcoinGrpcUpstream(
     }
 
     override fun isRunning(): Boolean {
-        return grpcHead.isRunning
+        return true
     }
 
     override fun start() {
-        grpcHead.start(remote)
     }
 
     override fun stop() {
-        grpcHead.stop()
     }
 
     override fun update(conf: BlockchainOuterClass.DescribeChain) {

src/main/kotlin/io/emeraldpay/dshackle/upstream/grpc/EthereumGrpcUpstream.kt

@@ -95,22 +95,20 @@ open class EthereumGrpcUpstream(
 
     private val log = LoggerFactory.getLogger(EthereumGrpcUpstream::class.java)
     private val upstreamStatus = GrpcUpstreamStatus()
-    private val grpcHead = GrpcHead(chain, this, blockConverter, reloadBlock)
+    private val grpcHead = GrpcHead(chain, this, remote, blockConverter, reloadBlock)
     private var capabilities: Set<Capability> = emptySet()
 
     private val defaultReader: Reader<JsonRpcRequest, JsonRpcResponse> = client.forSelector(Selector.empty)
     var timeout = Defaults.timeout
 
     override fun start() {
-        grpcHead.start(remote)
     }
 
     override fun isRunning(): Boolean {
-        return grpcHead.isRunning
+        return true
     }
 
     override fun stop() {
-        grpcHead.stop()
     }
 
     override fun update(conf: BlockchainOuterClass.DescribeChain) {

src/main/kotlin/io/emeraldpay/dshackle/upstream/grpc/GrpcHead.kt

@@ -37,6 +37,7 @@ import java.util.function.Function
 class GrpcHead(
     private val chain: Chain,
     private val parent: DefaultUpstream,
+    private val remote: ReactorBlockchainGrpc.ReactorBlockchainStub,
     /**
      * Converted from remote head details to the block container, which could be partial at this point
      */
@@ -56,10 +57,11 @@ class GrpcHead(
     /**
      * Initiate a new head subscription with connection to the remote
      */
-    fun start(remote: ReactorBlockchainGrpc.ReactorBlockchainStub) {
+    private fun internalStart(remote: ReactorBlockchainGrpc.ReactorBlockchainStub) {
         if (this.isRunning) {
             stop()
         }
+        log.debug("Start Head subscription to ${parent.getId()}")
 
         val source = Flux.concat(
             // first connect immediately
@@ -68,7 +70,7 @@ class GrpcHead(
             Flux.just(remote).repeat().delayElements(Defaults.retryConnection)
         ).flatMap(this::subscribeHead)
 
-        start(source)
+        internalStart(source)
     }
 
     fun subscribeHead(client: ReactorBlockchainGrpc.ReactorBlockchainStub): Publisher<BlockchainOuterClass.ChainHead> {
@@ -88,7 +90,7 @@ class GrpcHead(
     /**
      * Initiate a new head from provided source of head details
      */
-    fun start(source: Flux<BlockchainOuterClass.ChainHead>) {
+    private fun internalStart(source: Flux<BlockchainOuterClass.ChainHead>) {
         var blocks = source.map(converter)
             .distinctUntilChanged {
                 it.hash
@@ -112,7 +114,7 @@ class GrpcHead(
     }
 
     override fun start() {
-        log.error("Use start with provides source")
+        this.internalStart(remote)
     }
 
     override fun stop() {