Lower data timestamp (#404)

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

@@ -57,6 +57,7 @@ class StreamHead(
             .setSlot(block.slot)
             .setCurrentLowerBlock(ms.getLowerBlock().blockNumber)
             .setCurrentLowerSlot(ms.getLowerBlock().slot ?: 0)
+            .setCurrentLowerDataTimestamp(ms.getLowerBlock().timestamp)
             .setTimestamp(block.timestamp.toEpochMilli())
             .setWeight(ByteString.copyFrom(block.difficulty.toByteArray()))
             .setBlockId(block.hash.toHex())

src/main/kotlin/io/emeraldpay/dshackle/upstream/LowerBoundBlockDetector.kt

@@ -5,6 +5,7 @@ import org.slf4j.LoggerFactory
 import reactor.core.publisher.Flux
 import reactor.core.publisher.Mono
 import java.time.Duration
+import java.time.Instant
 import java.util.concurrent.atomic.AtomicReference
 
 typealias LowerBoundBlockDetectorBuilder = (Chain, Upstream) -> LowerBoundBlockDetector
@@ -41,11 +42,14 @@ abstract class LowerBoundBlockDetector(
     data class LowerBlockData(
         val blockNumber: Long,
         val slot: Long?,
+        val timestamp: Long,
     ) : Comparable<LowerBlockData> {
-        constructor(blockNumber: Long) : this(blockNumber, null)
+        constructor(blockNumber: Long) : this(blockNumber, null, Instant.now().epochSecond)
+
+        constructor(blockNumber: Long, slot: Long) : this(blockNumber, slot, Instant.now().epochSecond)
 
         companion object {
-            fun default() = LowerBlockData(0, 0)
+            fun default() = LowerBlockData(0, 0, 0)
         }
 
         override fun compareTo(other: LowerBlockData): Int {

src/main/kotlin/io/emeraldpay/dshackle/upstream/ethereum/EthereumLowerBoundBlockDetector.kt

@@ -33,6 +33,7 @@ class EthereumLowerBoundBlockDetector(
             "header for hash not found",
             "after last accepted block",
             "Version has either been pruned, or is for a future block", // cronos
+            "no historical RPC is available for this historical", // optimism
         )
     }