diff --git a/assignments/src/MV3500Cohort2019JulySeptember/projects/BrennenstuhlKnobelochMcCann/BRE_KNO_MCC_PC2_PC1_MCAST_PduReceiver.java b/assignments/src/MV3500Cohort2019JulySeptember/projects/BrennenstuhlKnobelochMcCann/BRE_KNO_MCC_PC2_PC1_MCAST_PduReceiver.java
index d61ca2c015f453bfb59b6b7f257471b6f5ca8f62..9c67fe6dd2e9a6fe2e193fdd8f594352f7ffecfd 100644
--- a/assignments/src/MV3500Cohort2019JulySeptember/projects/BrennenstuhlKnobelochMcCann/BRE_KNO_MCC_PC2_PC1_MCAST_PduReceiver.java
+++ b/assignments/src/MV3500Cohort2019JulySeptember/projects/BrennenstuhlKnobelochMcCann/BRE_KNO_MCC_PC2_PC1_MCAST_PduReceiver.java
@@ -1,6 +1,8 @@
 package MV3500Cohort2019JulySeptember.projects.BrennenstuhlKnobelochMcCann;
 
-import com.sun.corba.se.impl.orbutil.concurrent.Mutex;
+import com.sun.corba.se.impl.orbutil.concurrent.Mutex; // JDK 8
+// TODO JDK 13?
+// maybe https://crunchify.com/what-is-java-semaphore-and-mutex-java-concurrency-multithread-explained-with-example/
 import java.net.*;
 import java.io.*;
 
diff --git a/assignments/src/MV3500Cohort2019JulySeptember/projects/BrennenstuhlKnobelochMcCann/BRE_KNO_MCC_PC2_PC3_UNICAST_PduSender.java b/assignments/src/MV3500Cohort2019JulySeptember/projects/BrennenstuhlKnobelochMcCann/BRE_KNO_MCC_PC2_PC3_UNICAST_PduSender.java
index 53c4a670c5203662d755429bb4a9806f5a5594d9..87bc5b00219ba0bd3f18d45ec0556c5576490cb8 100755
--- a/assignments/src/MV3500Cohort2019JulySeptember/projects/BrennenstuhlKnobelochMcCann/BRE_KNO_MCC_PC2_PC3_UNICAST_PduSender.java
+++ b/assignments/src/MV3500Cohort2019JulySeptember/projects/BrennenstuhlKnobelochMcCann/BRE_KNO_MCC_PC2_PC3_UNICAST_PduSender.java
@@ -1,6 +1,8 @@
 package MV3500Cohort2019JulySeptember.projects.BrennenstuhlKnobelochMcCann;
 
-import com.sun.corba.se.impl.orbutil.concurrent.Mutex;
+import com.sun.corba.se.impl.orbutil.concurrent.Mutex; // JDK 8
+// TODO JDK 13?
+// maybe https://crunchify.com/what-is-java-semaphore-and-mutex-java-concurrency-multithread-explained-with-example/
 import java.util.*;
 
 import edu.nps.moves.dis7.*;