Use Objects.hashCode() when there is only one item to hash.
diff --git a/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/JsonTemplateLayout.java b/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/JsonTemplateLayout.java
index 9b8830c..1003599 100644
--- a/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/JsonTemplateLayout.java
+++ b/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/JsonTemplateLayout.java
@@ -559,8 +559,12 @@
 
         @Override
         public boolean equals(Object object) {
-            if (this == object) return true;
-            if (object == null || getClass() != object.getClass()) return false;
+            if (this == object) {
+                return true;
+            }
+            if (object == null || getClass() != object.getClass()) {
+                return false;
+            }
             EventTemplateAdditionalField that = (EventTemplateAdditionalField) object;
             return key.equals(that.key) &&
                     value.equals(that.value) &&
diff --git a/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/MapAccessor.java b/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/MapAccessor.java
index 2f97070..3deb2da 100644
--- a/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/MapAccessor.java
+++ b/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/MapAccessor.java
@@ -169,15 +169,19 @@
 
     @Override
     public boolean equals(final Object instance) {
-        if (this == instance) return true;
-        if (instance == null || getClass() != instance.getClass()) return false;
+        if (this == instance) {
+            return true;
+        }
+        if (instance == null || getClass() != instance.getClass()) {
+            return false;
+        }
         final MapAccessor that = (MapAccessor) instance;
         return map.equals(that.map);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(map);
+        return 31 + Objects.hashCode(map);
     }
 
     @Override
diff --git a/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/StringParameterParser.java b/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/StringParameterParser.java
index 041f2e3..2db794e 100644
--- a/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/StringParameterParser.java
+++ b/log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/StringParameterParser.java
@@ -77,15 +77,19 @@
 
         @Override
         public boolean equals(Object object) {
-            if (this == object) return true;
-            if (object == null || getClass() != object.getClass()) return false;
+            if (this == object) {
+                return true;
+            }
+            if (object == null || getClass() != object.getClass()) {
+                return false;
+            }
             StringValue that = (StringValue) object;
             return string.equals(that.string);
         }
 
         @Override
         public int hashCode() {
-            return Objects.hash(string);
+            return 31 + Objects.hashCode(string);
         }
 
         @Override
@@ -109,15 +113,19 @@
 
         @Override
         public boolean equals(Object object) {
-            if (this == object) return true;
-            if (object == null || getClass() != object.getClass()) return false;
+            if (this == object) {
+                return true;
+            }
+            if (object == null || getClass() != object.getClass()) {
+                return false;
+            }
             DoubleQuotedStringValue that = (DoubleQuotedStringValue) object;
             return doubleQuotedString.equals(that.doubleQuotedString);
         }
 
         @Override
         public int hashCode() {
-            return Objects.hash(doubleQuotedString);
+            return 31 + Objects.hashCode(doubleQuotedString);
         }
 
         @Override