diff --git a/ratis-common/src/main/java/org/apache/ratis/util/SizeInBytes.java b/ratis-common/src/main/java/org/apache/ratis/util/SizeInBytes.java
index 683f0da628..0756f4feee 100644
--- a/ratis-common/src/main/java/org/apache/ratis/util/SizeInBytes.java
+++ b/ratis-common/src/main/java/org/apache/ratis/util/SizeInBytes.java
@@ -33,14 +33,14 @@ public static SizeInBytes valueOf(long size) {
   }
 
   public static SizeInBytes valueOf(long n, TraditionalBinaryPrefix prefix) {
-    final long size = Objects.requireNonNull(prefix, "prefix = null").toLong(n);
+    final long size = Objects.requireNonNull(prefix, "prefix == null").toLong(n);
     final String input = n + " " + prefix.getSymbol();
     final String description = input + " (=" + size + ")";
     return new SizeInBytes(size, input, description);
   }
 
   public static SizeInBytes valueOf(String input) {
-    input = Objects.requireNonNull(input, "input = null").trim();
+    input = Objects.requireNonNull(input, "input == null").trim();
 
     final int last = input.length() - 1;
     final String s = "b".equalsIgnoreCase(input.substring(last))?
diff --git a/ratis-common/src/main/java/org/apache/ratis/util/TimeDuration.java b/ratis-common/src/main/java/org/apache/ratis/util/TimeDuration.java
index 2abdfdfaca..2a520083e0 100644
--- a/ratis-common/src/main/java/org/apache/ratis/util/TimeDuration.java
+++ b/ratis-common/src/main/java/org/apache/ratis/util/TimeDuration.java
@@ -144,7 +144,7 @@ public static long parse(String timeString, TimeUnit targetUnit) {
    * @return a {@link TimeDuration} in the target unit.
    */
   public static TimeDuration valueOf(String timeString, TimeUnit defaultUnit) {
-    Objects.requireNonNull(timeString, "timeString = null");
+    Objects.requireNonNull(timeString, "timeString == null");
     final String lower = timeString.trim().replace("_", "").toLowerCase();
     for(Abbreviation a : Abbreviation.values()) {
       for(String s : a.getSymbols()) {
@@ -172,7 +172,7 @@ public static TimeDuration valueOf(long duration, TimeUnit unit) {
 
   private TimeDuration(long duration, TimeUnit unit) {
     this.duration = duration;
-    this.unit = Objects.requireNonNull(unit, "unit = null");
+    this.unit = Objects.requireNonNull(unit, "unit == null");
   }
 
   /** @return the duration value. */
diff --git a/ratis-server-api/src/main/java/org/apache/ratis/statemachine/TransactionContext.java b/ratis-server-api/src/main/java/org/apache/ratis/statemachine/TransactionContext.java
index 6f08c4a55d..d6ff9a0833 100644
--- a/ratis-server-api/src/main/java/org/apache/ratis/statemachine/TransactionContext.java
+++ b/ratis-server-api/src/main/java/org/apache/ratis/statemachine/TransactionContext.java
@@ -235,7 +235,7 @@ public TransactionContext build() {
         return newTransactionContext(stateMachine, clientRequest,
             stateMachineLogEntry, logData, stateMachineData, stateMachineContext);
       } else {
-        Objects.requireNonNull(logEntry, "logEntry MUST NOT be null since clientRequest == null");
+        Objects.requireNonNull(logEntry, "logEntry must not be null since clientRequest == null");
         Preconditions.assertTrue(logEntry.hasStateMachineLogEntry(),
             () -> "Unexpected logEntry: stateMachineLogEntry not found, logEntry=" + logEntry);
         return newTransactionContext(serverRole, stateMachine, logEntry);
diff --git a/ratis-server/src/main/java/org/apache/ratis/server/impl/PendingRequest.java b/ratis-server/src/main/java/org/apache/ratis/server/impl/PendingRequest.java
index 4271d76162..d72fcde90b 100644
--- a/ratis-server/src/main/java/org/apache/ratis/server/impl/PendingRequest.java
+++ b/ratis-server/src/main/java/org/apache/ratis/server/impl/PendingRequest.java
@@ -64,7 +64,7 @@ RaftClientReply convert(RaftClientRequest q, RaftClientReply p) {
   }
 
   TermIndex getTermIndex() {
-    return Objects.requireNonNull(termIndex, "termIndex");
+    return Objects.requireNonNull(termIndex, "termIndex == null");
   }
 
   RaftClientRequest getRequest() {
diff --git a/ratis-server/src/main/java/org/apache/ratis/server/impl/RaftConfigurationImpl.java b/ratis-server/src/main/java/org/apache/ratis/server/impl/RaftConfigurationImpl.java
index 15a114cdb4..2e5cd58120 100644
--- a/ratis-server/src/main/java/org/apache/ratis/server/impl/RaftConfigurationImpl.java
+++ b/ratis-server/src/main/java/org/apache/ratis/server/impl/RaftConfigurationImpl.java
@@ -58,7 +58,7 @@ static final class Builder {
     private Builder() {}
 
     Builder setConf(PeerConfiguration conf) {
-      Objects.requireNonNull(conf);
+      Objects.requireNonNull(conf, "PeerConfiguration == null");
       Preconditions.assertTrue(this.conf == null, "conf is already set.");
       this.conf = conf;
       return this;
@@ -73,7 +73,7 @@ Builder setConf(Iterable<RaftPeer> peers, Iterable<RaftPeer> listeners) {
     }
 
     Builder setConf(RaftConfigurationImpl transitionalConf) {
-      Objects.requireNonNull(transitionalConf);
+      Objects.requireNonNull(transitionalConf, "transitionalConf == null");
       Preconditions.assertTrue(transitionalConf.isTransitional());
 
       Preconditions.assertTrue(!forceTransitional);
@@ -83,7 +83,7 @@ Builder setConf(RaftConfigurationImpl transitionalConf) {
 
 
     Builder setOldConf(PeerConfiguration oldConf) {
-      Objects.requireNonNull(oldConf);
+      Objects.requireNonNull(oldConf, "oldConf == null");
       Preconditions.assertTrue(this.oldConf == null, "oldConf is already set.");
       this.oldConf = oldConf;
       return this;
@@ -94,7 +94,7 @@ Builder setOldConf(Iterable<RaftPeer> oldPeers, Iterable<RaftPeer> oldListeners)
     }
 
     Builder setOldConf(RaftConfigurationImpl stableConf) {
-      Objects.requireNonNull(stableConf);
+      Objects.requireNonNull(stableConf, "stableConf == null");
       Preconditions.assertTrue(stableConf.isStable());
 
       Preconditions.assertTrue(!forceStable);
@@ -133,7 +133,7 @@ RaftConfigurationImpl build() {
 
   private RaftConfigurationImpl(PeerConfiguration conf, PeerConfiguration oldConf,
       long logEntryIndex) {
-    this.conf = Objects.requireNonNull(conf);
+    this.conf = Objects.requireNonNull(conf, "PeerConfiguration == null");
     this.oldConf = oldConf;
     this.logEntryIndex = logEntryIndex;
   }