diff --git a/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/BootNotificationConfirmation.java b/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/BootNotificationConfirmation.java
index 1d34cf423..46a696691 100644
--- a/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/BootNotificationConfirmation.java
+++ b/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/BootNotificationConfirmation.java
@@ -122,7 +122,7 @@ public Integer getInterval() {
    */
   @XmlElement
   public void setInterval(Integer interval) {
-    if (interval <= 0) {
+    if (interval < 0) {
       throw new PropertyConstraintException(interval, "interval be a positive value");
     }
 
@@ -172,7 +172,7 @@ public boolean equals(Object o) {
     if (this == o) return true;
     if (o == null || getClass() != o.getClass()) return false;
     BootNotificationConfirmation that = (BootNotificationConfirmation) o;
-    return interval == that.interval
+    return Objects.equals(interval, that.interval)
         && Objects.equals(currentTime, that.currentTime)
         && status == that.status;
   }
diff --git a/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/ChangeAvailabilityRequest.java b/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/ChangeAvailabilityRequest.java
index e2fb19648..47896d63e 100644
--- a/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/ChangeAvailabilityRequest.java
+++ b/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/ChangeAvailabilityRequest.java
@@ -131,7 +131,7 @@ public boolean equals(Object o) {
     if (this == o) return true;
     if (o == null || getClass() != o.getClass()) return false;
     ChangeAvailabilityRequest that = (ChangeAvailabilityRequest) o;
-    return connectorId == that.connectorId && type == that.type;
+    return Objects.equals(connectorId, that.connectorId) && type == that.type;
   }
 
   @Override
diff --git a/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/MeterValuesRequest.java b/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/MeterValuesRequest.java
index ee1893276..dcb382e84 100644
--- a/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/MeterValuesRequest.java
+++ b/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/core/MeterValuesRequest.java
@@ -148,8 +148,8 @@ public boolean equals(Object o) {
     if (this == o) return true;
     if (o == null || getClass() != o.getClass()) return false;
     MeterValuesRequest that = (MeterValuesRequest) o;
-    return connectorId == that.connectorId
-        && transactionId == that.transactionId
+    return Objects.equals(connectorId, that.connectorId)
+        && Objects.equals(transactionId, that.transactionId)
         && Arrays.equals(meterValue, that.meterValue);
   }
 
diff --git a/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/firmware/GetDiagnosticsRequest.java b/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/firmware/GetDiagnosticsRequest.java
index a8ba61820..4fd8deba1 100644
--- a/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/firmware/GetDiagnosticsRequest.java
+++ b/ocpp-v1_6/src/main/java/eu/chargetime/ocpp/model/firmware/GetDiagnosticsRequest.java
@@ -178,8 +178,8 @@ public boolean equals(Object o) {
     if (this == o) return true;
     if (o == null || getClass() != o.getClass()) return false;
     GetDiagnosticsRequest that = (GetDiagnosticsRequest) o;
-    return retries == that.retries
-        && retryInterval == that.retryInterval
+    return Objects.equals(retries, that.retries)
+        && Objects.equals(retryInterval, that.retryInterval)
         && Objects.equals(location, that.location)
         && Objects.equals(startTime, that.startTime)
         && Objects.equals(stopTime, that.stopTime);