From dbe0993fae2094a591e1aed90392f4af2706f230 Mon Sep 17 00:00:00 2001
From: Manfred Karrer <mk@nucleo.io>
Date: Wed, 26 Sep 2018 23:58:47 -0500
Subject: [PATCH] Fix nullpointer

---
 .../bisq/core/dao/state/blockchain/BaseBlock.java    | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/core/src/main/java/bisq/core/dao/state/blockchain/BaseBlock.java b/core/src/main/java/bisq/core/dao/state/blockchain/BaseBlock.java
index 3ea8349c9fb..ebc6c4b4f7f 100644
--- a/core/src/main/java/bisq/core/dao/state/blockchain/BaseBlock.java
+++ b/core/src/main/java/bisq/core/dao/state/blockchain/BaseBlock.java
@@ -19,8 +19,11 @@
 
 import io.bisq.generated.protobuffer.PB;
 
+import java.util.Optional;
+
 import lombok.Data;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 /**
@@ -33,6 +36,7 @@ public abstract class BaseBlock {
     protected final int height;
     protected final long time; // in ms
     protected final String hash;
+    @Nullable // in case of first block in the blockchain
     protected final String previousBlockHash;
 
     BaseBlock(int height, long time, String hash, String previousBlockHash) {
@@ -48,11 +52,13 @@ public abstract class BaseBlock {
     ///////////////////////////////////////////////////////////////////////////////////////////
 
     PB.BaseBlock.Builder getBaseBlockBuilder() {
-        return PB.BaseBlock.newBuilder()
+        PB.BaseBlock.Builder builder = PB.BaseBlock.newBuilder()
                 .setHeight(height)
                 .setTime(time)
-                .setHash(hash)
-                .setPreviousBlockHash(previousBlockHash);
+                .setHash(hash);
+        Optional.ofNullable(previousBlockHash).ifPresent(builder::setPreviousBlockHash);
+        return builder;
+
     }
 
     @Override