diff --git a/.gitignore b/.gitignore
index 8642ca27..3d41d1db 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,6 +9,7 @@
 
 # Mobile Tools for Java (J2ME)
 .mtj.tmp/
+bin/
 
 # Package Files #
 *.jar
@@ -58,8 +59,3 @@ server/src/test/resources/test_output/
 
 # simulator files, this files are un-tarred before build
 /simulator/src/main/resources/block-0.0.3/
-/common/bin
-/server/bin
-/simulator/bin
-/stream/bin
-/suites/bin
diff --git a/simulator/src/main/java/com/hedera/block/simulator/config/data/StreamStatus.java b/simulator/src/main/java/com/hedera/block/simulator/config/data/StreamStatus.java
index 3a2a8b61..97d2fe2e 100644
--- a/simulator/src/main/java/com/hedera/block/simulator/config/data/StreamStatus.java
+++ b/simulator/src/main/java/com/hedera/block/simulator/config/data/StreamStatus.java
@@ -19,6 +19,8 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * Represents the status of the stream.
  *
@@ -87,7 +89,8 @@ public Builder consumedBlocks(int consumedBlocks) {
          * @return the builder instance
          */
         public Builder lastKnownPublisherStatuses(List<String> lastKnownPublisherStatuses) {
-            this.lastKnownPublisherStatuses = lastKnownPublisherStatuses;
+            requireNonNull(lastKnownPublisherStatuses);
+            this.lastKnownPublisherStatuses = new ArrayList<>(lastKnownPublisherStatuses);
             return this;
         }
 
@@ -98,7 +101,8 @@ public Builder lastKnownPublisherStatuses(List<String> lastKnownPublisherStatuse
          * @return the builder instance
          */
         public Builder lastKnownConsumersStatuses(List<String> lastKnownConsumersStatuses) {
-            this.lastKnownConsumersStatuses = lastKnownConsumersStatuses;
+            requireNonNull(lastKnownConsumersStatuses);
+            this.lastKnownConsumersStatuses = new ArrayList<>(lastKnownConsumersStatuses);
             return this;
         }