Implementing retry logic to restTemplate (#17375)

* Implementing retry logic to restTemplate

* Fixing the issue

* Adding import

* Fix

* Fix

* minor update, add tests

* fix

* Adding the maxRetryAttempt, threadWaitTime as additionalProperty

* Updating the apiClient

* Removing reduntant variable

* Generating samples

* Fixing format

---------

Co-authored-by: Rubini <rubini@Rubinis-MacBook-Air.local>
Co-authored-by: William Cheng <wing328hk@gmail.com>

modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenConstants.java

@@ -438,4 +438,8 @@ public class CodegenConstants {
 
     public static final String GENERATE_MARSHAL_JSON = "generateMarshalJSON";
     public static final String GENERATE_MARSHAL_JSON_DESC = "Generate MarshalJSON method";
+
+    public static final String MAX_ATTEMPTS_FOR_RETRY = "maxAttemptsForRetry";
+
+    public static final String WAIT_TIME_OF_THREAD = "waitTimeMillis";
 }

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java

@@ -139,6 +139,9 @@ public class JavaClientCodegen extends AbstractJavaCodegen
     protected boolean generateClientAsBean = false;
     protected boolean useEnumCaseInsensitive = false;
 
+    protected int maxAttemptsForRetry = 1;
+    protected long waitTimeMillis = 10l;
+
     private static class MpRestClientVersion {
         public final String rootPackage;
         public final String pomTemplate;
@@ -465,6 +468,20 @@ public class JavaClientCodegen extends AbstractJavaCodegen
         if (additionalProperties.containsKey(USE_ENUM_CASE_INSENSITIVE)) {
             this.setUseEnumCaseInsensitive(Boolean.parseBoolean(additionalProperties.get(USE_ENUM_CASE_INSENSITIVE).toString()));
         }
+
+        if (additionalProperties.containsKey(CodegenConstants.MAX_ATTEMPTS_FOR_RETRY)) {
+            this.setMaxAttemptsForRetry(Integer.parseInt(additionalProperties.get(CodegenConstants.MAX_ATTEMPTS_FOR_RETRY).toString()));
+        }
+        else {
+            additionalProperties.put(CodegenConstants.MAX_ATTEMPTS_FOR_RETRY, maxAttemptsForRetry);
+        }
+
+        if (additionalProperties.containsKey(CodegenConstants.WAIT_TIME_OF_THREAD)) {
+            this.setWaitTimeMillis(Long.parseLong((additionalProperties.get(CodegenConstants.WAIT_TIME_OF_THREAD).toString())));
+        }
+        else {
+            additionalProperties.put(CodegenConstants.WAIT_TIME_OF_THREAD, waitTimeMillis);
+        }
         writePropertyBack(USE_ENUM_CASE_INSENSITIVE, useEnumCaseInsensitive);
 
         final String invokerFolder = (sourceFolder + '/' + invokerPackage).replace(".", "/");
@@ -1240,6 +1257,14 @@ public class JavaClientCodegen extends AbstractJavaCodegen
         this.useEnumCaseInsensitive = useEnumCaseInsensitive;
     }
 
+    public void setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry= maxAttemptsForRetry;
+    }
+
+    public void setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis= waitTimeMillis;
+    }
+
     /**
      * Serialization library.
      *

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

@@ -31,6 +31,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestClientException;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -105,6 +106,10 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
     private HttpHeaders defaultHeaders = new HttpHeaders();
     private MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<String, String>();
 
+    private int maxAttemptsForRetry = {{maxAttemptsForRetry}};
+
+    private long waitTimeMillis = {{waitTimeMillis}};
+
     private String basePath = "{{basePath}}";
 
     private RestTemplate restTemplate;
@@ -167,6 +172,46 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         return this;
     }
 
+    /**
+     * Get the max attempts for retry
+     *
+     * @return int the max attempts
+     */
+    public int getMaxAttemptsForRetry() {
+        return maxAttemptsForRetry;
+    }
+
+    /**
+     * Set the max attempts for retry
+     *
+     * @param getMaxAttemptsForRetry the max attempts for retry
+     * @return ApiClient this client
+     */
+    public ApiClient setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry = maxAttemptsForRetry;
+        return this;
+    }
+
+    /**
+     * Get the wait time in milliseconds
+     *
+     * @return long wait time in milliseconds
+     */
+    public long getWaitTimeMillis() {
+        return waitTimeMillis;
+    }
+
+    /**
+     * Set the wait time in milliseconds
+     *
+     * @param waitTimeMillis the wait time in milliseconds
+     * @return ApiClient this client
+     */
+    public ApiClient setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis = waitTimeMillis;
+        return this;
+    }
+
     /**
      * Get authentications (key: authentication name, value: authentication).
      *
@@ -721,7 +766,23 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
 
         RequestEntity<Object> requestEntity = requestBuilder.body(selectBody(body, formParams, contentType));
 
-        ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);
+        ResponseEntity<T> responseEntity = null;
+        int attempts = 0;
+        while (attempts < maxAttemptsForRetry) {
+            try {
+                responseEntity = restTemplate.exchange(requestEntity, returnType);
+                break;
+            } catch (HttpServerErrorException ex) {
+                attempts++;
+                if (attempts < maxAttemptsForRetry) {
+                    try {
+                        Thread.sleep(waitTimeMillis);
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
+            }
+        }
 
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;

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

@@ -22,6 +22,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestClientException;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -79,6 +80,10 @@ public class ApiClient extends JavaTimeFormatter {
     private HttpHeaders defaultHeaders = new HttpHeaders();
     private MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<String, String>();
 
+    private int maxAttemptsForRetry = 1;
+
+    private long waitTimeMillis = 10;
+
     private String basePath = "http://localhost:3000";
 
     private RestTemplate restTemplate;
@@ -136,6 +141,46 @@ public class ApiClient extends JavaTimeFormatter {
         return this;
     }
 
+    /**
+     * Get the max attempts for retry
+     *
+     * @return int the max attempts
+     */
+    public int getMaxAttemptsForRetry() {
+        return maxAttemptsForRetry;
+    }
+
+    /**
+     * Set the max attempts for retry
+     *
+     * @param getMaxAttemptsForRetry the max attempts for retry
+     * @return ApiClient this client
+     */
+    public ApiClient setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry = maxAttemptsForRetry;
+        return this;
+    }
+
+    /**
+     * Get the wait time in milliseconds
+     *
+     * @return long wait time in milliseconds
+     */
+    public long getWaitTimeMillis() {
+        return waitTimeMillis;
+    }
+
+    /**
+     * Set the wait time in milliseconds
+     *
+     * @param waitTimeMillis the wait time in milliseconds
+     * @return ApiClient this client
+     */
+    public ApiClient setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis = waitTimeMillis;
+        return this;
+    }
+
     /**
      * Get authentications (key: authentication name, value: authentication).
      *
@@ -637,7 +682,23 @@ public class ApiClient extends JavaTimeFormatter {
 
         RequestEntity<Object> requestEntity = requestBuilder.body(selectBody(body, formParams, contentType));
 
-        ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);
+        ResponseEntity<T> responseEntity = null;
+        int attempts = 0;
+        while (attempts < maxAttemptsForRetry) {
+            try {
+                responseEntity = restTemplate.exchange(requestEntity, returnType);
+                break;
+            } catch (HttpServerErrorException ex) {
+                attempts++;
+                if (attempts < maxAttemptsForRetry) {
+                    try {
+                        Thread.sleep(waitTimeMillis);
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
+            }
+        }
 
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;

samples/client/echo_api/java/resttemplate/src/test/java/org/openapitools/client/CustomTest.java

@@ -0,0 +1,54 @@
+/*
+ * Echo Server API
+ * Echo Server API
+ *
+ * The version of the OpenAPI document: 0.1.0
+ * Contact: team@openapitools.oprg
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.junit.Assert;
+import org.openapitools.client.api.*;
+import org.openapitools.client.model.*;
+import org.junit.Test;
+import org.junit.Ignore;
+
+import java.io.IOException;
+import java.util.*;
+
+
+/**
+ * API tests
+ */
+public class CustomTest {
+
+    private final QueryApi api = new QueryApi();
+    private final BodyApi bodyApi = new BodyApi();
+
+    /**
+     * Test body parameter(s)
+     * <p>
+     * Test body parameter(s)
+     *
+     */
+    @Test
+    public void testEchoBodyPet() {
+        Pet pet = new Pet().id(12345L).name("Hello World").
+                photoUrls(Arrays.asList(new String[]{"http://a.com", "http://b.com"})).category(new Category().id(987L).name("new category"));
+
+        Pet p = bodyApi.testEchoBodyPet(pet);
+        Assert.assertNotNull(p);
+        Assert.assertEquals("Hello World", p.getName());
+        Assert.assertEquals(Long.valueOf(12345L), p.getId());
+
+        // response is empty body
+        Pet p2 = bodyApi.testEchoBodyPet(null);
+        Assert.assertNull(p2);
+    }
+}

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

@@ -22,6 +22,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestClientException;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -77,6 +78,10 @@ public class ApiClient extends JavaTimeFormatter {
     private HttpHeaders defaultHeaders = new HttpHeaders();
     private MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<String, String>();
 
+    private int maxAttemptsForRetry = 1;
+
+    private long waitTimeMillis = 10;
+
     private String basePath = "http://localhost";
 
     private RestTemplate restTemplate;
@@ -132,6 +137,46 @@ public class ApiClient extends JavaTimeFormatter {
         return this;
     }
 
+    /**
+     * Get the max attempts for retry
+     *
+     * @return int the max attempts
+     */
+    public int getMaxAttemptsForRetry() {
+        return maxAttemptsForRetry;
+    }
+
+    /**
+     * Set the max attempts for retry
+     *
+     * @param getMaxAttemptsForRetry the max attempts for retry
+     * @return ApiClient this client
+     */
+    public ApiClient setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry = maxAttemptsForRetry;
+        return this;
+    }
+
+    /**
+     * Get the wait time in milliseconds
+     *
+     * @return long wait time in milliseconds
+     */
+    public long getWaitTimeMillis() {
+        return waitTimeMillis;
+    }
+
+    /**
+     * Set the wait time in milliseconds
+     *
+     * @param waitTimeMillis the wait time in milliseconds
+     * @return ApiClient this client
+     */
+    public ApiClient setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis = waitTimeMillis;
+        return this;
+    }
+
     /**
      * Get authentications (key: authentication name, value: authentication).
      *
@@ -580,7 +625,23 @@ public class ApiClient extends JavaTimeFormatter {
 
         RequestEntity<Object> requestEntity = requestBuilder.body(selectBody(body, formParams, contentType));
 
-        ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);
+        ResponseEntity<T> responseEntity = null;
+        int attempts = 0;
+        while (attempts < maxAttemptsForRetry) {
+            try {
+                responseEntity = restTemplate.exchange(requestEntity, returnType);
+                break;
+            } catch (HttpServerErrorException ex) {
+                attempts++;
+                if (attempts < maxAttemptsForRetry) {
+                    try {
+                        Thread.sleep(waitTimeMillis);
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
+            }
+        }
 
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;

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

@@ -22,6 +22,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestClientException;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -79,6 +80,10 @@ public class ApiClient extends JavaTimeFormatter {
     private HttpHeaders defaultHeaders = new HttpHeaders();
     private MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<String, String>();
 
+    private int maxAttemptsForRetry = 1;
+
+    private long waitTimeMillis = 10;
+
     private String basePath = "http://petstore.swagger.io/v2";
 
     private RestTemplate restTemplate;
@@ -136,6 +141,46 @@ public class ApiClient extends JavaTimeFormatter {
         return this;
     }
 
+    /**
+     * Get the max attempts for retry
+     *
+     * @return int the max attempts
+     */
+    public int getMaxAttemptsForRetry() {
+        return maxAttemptsForRetry;
+    }
+
+    /**
+     * Set the max attempts for retry
+     *
+     * @param getMaxAttemptsForRetry the max attempts for retry
+     * @return ApiClient this client
+     */
+    public ApiClient setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry = maxAttemptsForRetry;
+        return this;
+    }
+
+    /**
+     * Get the wait time in milliseconds
+     *
+     * @return long wait time in milliseconds
+     */
+    public long getWaitTimeMillis() {
+        return waitTimeMillis;
+    }
+
+    /**
+     * Set the wait time in milliseconds
+     *
+     * @param waitTimeMillis the wait time in milliseconds
+     * @return ApiClient this client
+     */
+    public ApiClient setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis = waitTimeMillis;
+        return this;
+    }
+
     /**
      * Get authentications (key: authentication name, value: authentication).
      *
@@ -629,7 +674,23 @@ public class ApiClient extends JavaTimeFormatter {
 
         RequestEntity<Object> requestEntity = requestBuilder.body(selectBody(body, formParams, contentType));
 
-        ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);
+        ResponseEntity<T> responseEntity = null;
+        int attempts = 0;
+        while (attempts < maxAttemptsForRetry) {
+            try {
+                responseEntity = restTemplate.exchange(requestEntity, returnType);
+                break;
+            } catch (HttpServerErrorException ex) {
+                attempts++;
+                if (attempts < maxAttemptsForRetry) {
+                    try {
+                        Thread.sleep(waitTimeMillis);
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
+            }
+        }
 
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;

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

@@ -22,6 +22,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestClientException;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -79,6 +80,10 @@ public class ApiClient extends JavaTimeFormatter {
     private HttpHeaders defaultHeaders = new HttpHeaders();
     private MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<String, String>();
 
+    private int maxAttemptsForRetry = 1;
+
+    private long waitTimeMillis = 10;
+
     private String basePath = "http://petstore.swagger.io/v2";
 
     private RestTemplate restTemplate;
@@ -136,6 +141,46 @@ public class ApiClient extends JavaTimeFormatter {
         return this;
     }
 
+    /**
+     * Get the max attempts for retry
+     *
+     * @return int the max attempts
+     */
+    public int getMaxAttemptsForRetry() {
+        return maxAttemptsForRetry;
+    }
+
+    /**
+     * Set the max attempts for retry
+     *
+     * @param getMaxAttemptsForRetry the max attempts for retry
+     * @return ApiClient this client
+     */
+    public ApiClient setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry = maxAttemptsForRetry;
+        return this;
+    }
+
+    /**
+     * Get the wait time in milliseconds
+     *
+     * @return long wait time in milliseconds
+     */
+    public long getWaitTimeMillis() {
+        return waitTimeMillis;
+    }
+
+    /**
+     * Set the wait time in milliseconds
+     *
+     * @param waitTimeMillis the wait time in milliseconds
+     * @return ApiClient this client
+     */
+    public ApiClient setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis = waitTimeMillis;
+        return this;
+    }
+
     /**
      * Get authentications (key: authentication name, value: authentication).
      *
@@ -629,7 +674,23 @@ public class ApiClient extends JavaTimeFormatter {
 
         RequestEntity<Object> requestEntity = requestBuilder.body(selectBody(body, formParams, contentType));
 
-        ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);
+        ResponseEntity<T> responseEntity = null;
+        int attempts = 0;
+        while (attempts < maxAttemptsForRetry) {
+            try {
+                responseEntity = restTemplate.exchange(requestEntity, returnType);
+                break;
+            } catch (HttpServerErrorException ex) {
+                attempts++;
+                if (attempts < maxAttemptsForRetry) {
+                    try {
+                        Thread.sleep(waitTimeMillis);
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
+            }
+        }
 
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;

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

@@ -22,6 +22,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestClientException;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -79,6 +80,10 @@ public class ApiClient extends JavaTimeFormatter {
     private HttpHeaders defaultHeaders = new HttpHeaders();
     private MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<String, String>();
 
+    private int maxAttemptsForRetry = 1;
+
+    private long waitTimeMillis = 10;
+
     private String basePath = "http://petstore.swagger.io/v2";
 
     private RestTemplate restTemplate;
@@ -136,6 +141,46 @@ public class ApiClient extends JavaTimeFormatter {
         return this;
     }
 
+    /**
+     * Get the max attempts for retry
+     *
+     * @return int the max attempts
+     */
+    public int getMaxAttemptsForRetry() {
+        return maxAttemptsForRetry;
+    }
+
+    /**
+     * Set the max attempts for retry
+     *
+     * @param getMaxAttemptsForRetry the max attempts for retry
+     * @return ApiClient this client
+     */
+    public ApiClient setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry = maxAttemptsForRetry;
+        return this;
+    }
+
+    /**
+     * Get the wait time in milliseconds
+     *
+     * @return long wait time in milliseconds
+     */
+    public long getWaitTimeMillis() {
+        return waitTimeMillis;
+    }
+
+    /**
+     * Set the wait time in milliseconds
+     *
+     * @param waitTimeMillis the wait time in milliseconds
+     * @return ApiClient this client
+     */
+    public ApiClient setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis = waitTimeMillis;
+        return this;
+    }
+
     /**
      * Get authentications (key: authentication name, value: authentication).
      *
@@ -629,7 +674,23 @@ public class ApiClient extends JavaTimeFormatter {
 
         RequestEntity<Object> requestEntity = requestBuilder.body(selectBody(body, formParams, contentType));
 
-        ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);
+        ResponseEntity<T> responseEntity = null;
+        int attempts = 0;
+        while (attempts < maxAttemptsForRetry) {
+            try {
+                responseEntity = restTemplate.exchange(requestEntity, returnType);
+                break;
+            } catch (HttpServerErrorException ex) {
+                attempts++;
+                if (attempts < maxAttemptsForRetry) {
+                    try {
+                        Thread.sleep(waitTimeMillis);
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
+            }
+        }
 
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;

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

@@ -27,6 +27,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestClientException;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -86,6 +87,10 @@ public class ApiClient extends JavaTimeFormatter {
     private HttpHeaders defaultHeaders = new HttpHeaders();
     private MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<String, String>();
 
+    private int maxAttemptsForRetry = 1;
+
+    private long waitTimeMillis = 10;
+
     private String basePath = "http://petstore.swagger.io:80/v2";
 
     private RestTemplate restTemplate;
@@ -146,6 +151,46 @@ public class ApiClient extends JavaTimeFormatter {
         return this;
     }
 
+    /**
+     * Get the max attempts for retry
+     *
+     * @return int the max attempts
+     */
+    public int getMaxAttemptsForRetry() {
+        return maxAttemptsForRetry;
+    }
+
+    /**
+     * Set the max attempts for retry
+     *
+     * @param getMaxAttemptsForRetry the max attempts for retry
+     * @return ApiClient this client
+     */
+    public ApiClient setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry = maxAttemptsForRetry;
+        return this;
+    }
+
+    /**
+     * Get the wait time in milliseconds
+     *
+     * @return long wait time in milliseconds
+     */
+    public long getWaitTimeMillis() {
+        return waitTimeMillis;
+    }
+
+    /**
+     * Set the wait time in milliseconds
+     *
+     * @param waitTimeMillis the wait time in milliseconds
+     * @return ApiClient this client
+     */
+    public ApiClient setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis = waitTimeMillis;
+        return this;
+    }
+
     /**
      * Get authentications (key: authentication name, value: authentication).
      *
@@ -692,7 +737,23 @@ public class ApiClient extends JavaTimeFormatter {
 
         RequestEntity<Object> requestEntity = requestBuilder.body(selectBody(body, formParams, contentType));
 
-        ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);
+        ResponseEntity<T> responseEntity = null;
+        int attempts = 0;
+        while (attempts < maxAttemptsForRetry) {
+            try {
+                responseEntity = restTemplate.exchange(requestEntity, returnType);
+                break;
+            } catch (HttpServerErrorException ex) {
+                attempts++;
+                if (attempts < maxAttemptsForRetry) {
+                    try {
+                        Thread.sleep(waitTimeMillis);
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
+            }
+        }
 
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;

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

@@ -22,6 +22,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
 import org.springframework.util.StringUtils;
+import org.springframework.web.client.HttpServerErrorException;
 import org.springframework.web.client.RestClientException;
 import org.springframework.web.client.RestTemplate;
 import org.springframework.web.util.UriComponentsBuilder;
@@ -81,6 +82,10 @@ public class ApiClient extends JavaTimeFormatter {
     private HttpHeaders defaultHeaders = new HttpHeaders();
     private MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<String, String>();
 
+    private int maxAttemptsForRetry = 1;
+
+    private long waitTimeMillis = 10;
+
     private String basePath = "http://petstore.swagger.io:80/v2";
 
     private RestTemplate restTemplate;
@@ -141,6 +146,46 @@ public class ApiClient extends JavaTimeFormatter {
         return this;
     }
 
+    /**
+     * Get the max attempts for retry
+     *
+     * @return int the max attempts
+     */
+    public int getMaxAttemptsForRetry() {
+        return maxAttemptsForRetry;
+    }
+
+    /**
+     * Set the max attempts for retry
+     *
+     * @param getMaxAttemptsForRetry the max attempts for retry
+     * @return ApiClient this client
+     */
+    public ApiClient setMaxAttemptsForRetry(int maxAttemptsForRetry) {
+        this.maxAttemptsForRetry = maxAttemptsForRetry;
+        return this;
+    }
+
+    /**
+     * Get the wait time in milliseconds
+     *
+     * @return long wait time in milliseconds
+     */
+    public long getWaitTimeMillis() {
+        return waitTimeMillis;
+    }
+
+    /**
+     * Set the wait time in milliseconds
+     *
+     * @param waitTimeMillis the wait time in milliseconds
+     * @return ApiClient this client
+     */
+    public ApiClient setWaitTimeMillis(long waitTimeMillis) {
+        this.waitTimeMillis = waitTimeMillis;
+        return this;
+    }
+
     /**
      * Get authentications (key: authentication name, value: authentication).
      *
@@ -687,7 +732,23 @@ public class ApiClient extends JavaTimeFormatter {
 
         RequestEntity<Object> requestEntity = requestBuilder.body(selectBody(body, formParams, contentType));
 
-        ResponseEntity<T> responseEntity = restTemplate.exchange(requestEntity, returnType);
+        ResponseEntity<T> responseEntity = null;
+        int attempts = 0;
+        while (attempts < maxAttemptsForRetry) {
+            try {
+                responseEntity = restTemplate.exchange(requestEntity, returnType);
+                break;
+            } catch (HttpServerErrorException ex) {
+                attempts++;
+                if (attempts < maxAttemptsForRetry) {
+                    try {
+                        Thread.sleep(waitTimeMillis);
+                    } catch (InterruptedException e) {
+                        Thread.currentThread().interrupt();
+                    }
+                }
+            }
+        }
 
         if (responseEntity.getStatusCode().is2xxSuccessful()) {
             return responseEntity;