Fix for handling error in resttemplate (#17381)

* Fix with handling error

* Fix with handling error

modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache

@@ -784,6 +784,10 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
             }
         }
 
+        if (responseEntity == null) {
+            throw new RestClientException("API returned HttpServerErrorException");
+        }
+
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;
         } else {

samples/client/echo_api/java/resttemplate/src/main/java/org/openapitools/client/ApiClient.java

@@ -700,6 +700,10 @@ public class ApiClient extends JavaTimeFormatter {
             }
         }
 
+        if (responseEntity == null) {
+            throw new RestClientException("API returned HttpServerErrorException");
+        }
+
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;
         } else {

samples/client/others/java/resttemplate-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java

@@ -643,6 +643,10 @@ public class ApiClient extends JavaTimeFormatter {
             }
         }
 
+        if (responseEntity == null) {
+            throw new RestClientException("API returned HttpServerErrorException");
+        }
+
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;
         } else {

samples/client/petstore/java/resttemplate-jakarta/src/main/java/org/openapitools/client/ApiClient.java

@@ -692,6 +692,10 @@ public class ApiClient extends JavaTimeFormatter {
             }
         }
 
+        if (responseEntity == null) {
+            throw new RestClientException("API returned HttpServerErrorException");
+        }
+
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;
         } else {

samples/client/petstore/java/resttemplate-swagger1/src/main/java/org/openapitools/client/ApiClient.java

@@ -692,6 +692,10 @@ public class ApiClient extends JavaTimeFormatter {
             }
         }
 
+        if (responseEntity == null) {
+            throw new RestClientException("API returned HttpServerErrorException");
+        }
+
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;
         } else {

samples/client/petstore/java/resttemplate-swagger2/src/main/java/org/openapitools/client/ApiClient.java

@@ -692,6 +692,10 @@ public class ApiClient extends JavaTimeFormatter {
             }
         }
 
+        if (responseEntity == null) {
+            throw new RestClientException("API returned HttpServerErrorException");
+        }
+
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;
         } else {

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/ApiClient.java

@@ -755,6 +755,10 @@ public class ApiClient extends JavaTimeFormatter {
             }
         }
 
+        if (responseEntity == null) {
+            throw new RestClientException("API returned HttpServerErrorException");
+        }
+
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;
         } else {

samples/client/petstore/java/resttemplate/src/main/java/org/openapitools/client/ApiClient.java

@@ -750,6 +750,10 @@ public class ApiClient extends JavaTimeFormatter {
             }
         }
 
+        if (responseEntity == null) {
+            throw new RestClientException("API returned HttpServerErrorException");
+        }
+
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;
         } else {