[java] [resttemplate] Add support for a bearer token supplier to OAuth based RestTemplate clients

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

@@ -331,9 +331,18 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
      * @param accessToken Access token
      */
     public void setAccessToken(String accessToken) {
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Helper method to set the supplier of access tokens for OAuth2 authentication.
+     *
+     * @param tokenSupplier The supplier of bearer tokens
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
         for (Authentication auth : authentications.values()) {
             if (auth instanceof OAuth) {
-                ((OAuth) auth).setAccessToken(accessToken);
+                ((OAuth) auth).setAccessToken(tokenSupplier);
                 return;
             }
         }

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

@@ -1,24 +1,48 @@
 package {{invokerPackage}}.auth;
 
+import java.util.Optional;
+import java.util.function.Supplier;
 import org.springframework.http.HttpHeaders;
 import org.springframework.util.MultiValueMap;
 
+/**
+ * Provides support for RFC 6750 - Bearer Token usage for OAUTH 2.0 Authorization.
+ */
 {{>generatedAnnotation}}
 public class OAuth implements Authentication {
-    private String accessToken;
+    private Supplier<String> tokenSupplier;
 
+    /**
+     * Returns the bearer token used for Authorization.
+     *
+     * @return The bearer token
+     */
     public String getAccessToken() {
-        return accessToken;
+        return tokenSupplier.get();
     }
 
+    /**
+     * Sets the bearer access token used for Authorization.
+     *
+     * @param bearerToken The bearer token to send in the Authorization header
+     */
     public void setAccessToken(String accessToken) {
-        this.accessToken = accessToken;
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Sets the supplier of bearer tokens used for Authorization.
+     *
+     * @param tokenSupplier The supplier of bearer tokens to send in the Authorization header
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
+        this.tokenSupplier = tokenSupplier;
     }
 
     @Override
     public void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams) {
-        if (accessToken != null) {
-            headerParams.add(HttpHeaders.AUTHORIZATION, "Bearer " + accessToken);
-        }
+        Optional.ofNullable(tokenSupplier).map(Supplier::get).ifPresent(accessToken ->
+            headerParams.add(HttpHeaders.AUTHORIZATION, "Bearer " + accessToken)
+        );
     }
 }

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java

@@ -2889,4 +2889,38 @@ void shouldGenerateCorrectJaxbAnnotations(Library library) {
             .containsWithNameAndAttributes("XmlElement", Map.of("name", "\"item\""))
             .containsWithNameAndAttributes("XmlElementWrapper", Map.of("name", "\"activities-array\""));
     }
+
+
+    @Test
+    public void shouldGenerateOAuthTokenSuppliers() {
+
+        final Map<String, File> files = generateFromContract(
+            "src/test/resources/3_0/java/oauth.yaml",
+            JavaClientCodegen.RESTTEMPLATE
+        );
+
+        final JavaFileAssert apiClient = JavaFileAssert.assertThat(files.get("ApiClient.java"))
+            .printFileContent();
+        apiClient
+            .assertMethod("setAccessToken", "String")
+            .bodyContainsLines("setAccessToken(() -> accessToken);");
+        apiClient
+            .assertMethod("setAccessToken", "Supplier<String>")
+            .bodyContainsLines("((OAuth) auth).setAccessToken(tokenSupplier);");
+
+        final JavaFileAssert oAuth = JavaFileAssert.assertThat(files.get("OAuth.java"))
+            .printFileContent();
+        oAuth
+            .assertMethod("setAccessToken", "String")
+            .bodyContainsLines("setAccessToken(() -> accessToken);");
+        oAuth
+            .assertMethod("setAccessToken", "Supplier<String>")
+            .bodyContainsLines("this.tokenSupplier = tokenSupplier;");
+        oAuth
+            .assertMethod("applyToParams")
+            .bodyContainsLines("Optional.ofNullable(tokenSupplier).map(Supplier::get).ifPresent(accessToken ->")
+            .bodyContainsLines("headerParams.add(HttpHeaders.AUTHORIZATION, \"Bearer \" + accessToken)");
+
+    }
+
 }

modules/openapi-generator/src/test/resources/3_0/java/oauth.yaml

@@ -0,0 +1,28 @@
+openapi: 3.0.3
+
+info:
+  title: Test OAuth code generation
+  description: Tests OAuth code generation
+  version: 1.0.0
+
+servers:
+  - url: http://localhost:8080
+
+paths:
+  /api/something:
+    get:
+      responses:
+        204:
+          description: Success!
+
+components:
+  securitySchemes:
+    oAuth:
+      type: oauth2
+      flows:
+        implicit:
+          authorizationUrl: ''
+          scopes: {}
+
+security:
+  - oAuth: []

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

@@ -240,9 +240,18 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
      * @param accessToken Access token
      */
     public void setAccessToken(String accessToken) {
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Helper method to set the supplier of access tokens for OAuth2 authentication.
+     *
+     * @param tokenSupplier The supplier of bearer tokens
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
         for (Authentication auth : authentications.values()) {
             if (auth instanceof OAuth) {
-                ((OAuth) auth).setAccessToken(accessToken);
+                ((OAuth) auth).setAccessToken(tokenSupplier);
                 return;
             }
         }

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

@@ -1,24 +1,48 @@
 package org.openapitools.client.auth;
 
+import java.util.Optional;
+import java.util.function.Supplier;
 import org.springframework.http.HttpHeaders;
 import org.springframework.util.MultiValueMap;
 
+/**
+ * Provides support for RFC 6750 - Bearer Token usage for OAUTH 2.0 Authorization.
+ */
 @jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.7.0-SNAPSHOT")
 public class OAuth implements Authentication {
-    private String accessToken;
+    private Supplier<String> tokenSupplier;
 
+    /**
+     * Returns the bearer token used for Authorization.
+     *
+     * @return The bearer token
+     */
     public String getAccessToken() {
-        return accessToken;
+        return tokenSupplier.get();
     }
 
+    /**
+     * Sets the bearer access token used for Authorization.
+     *
+     * @param bearerToken The bearer token to send in the Authorization header
+     */
     public void setAccessToken(String accessToken) {
-        this.accessToken = accessToken;
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Sets the supplier of bearer tokens used for Authorization.
+     *
+     * @param tokenSupplier The supplier of bearer tokens to send in the Authorization header
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
+        this.tokenSupplier = tokenSupplier;
     }
 
     @Override
     public void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams) {
-        if (accessToken != null) {
-            headerParams.add(HttpHeaders.AUTHORIZATION, "Bearer " + accessToken);
-        }
+        Optional.ofNullable(tokenSupplier).map(Supplier::get).ifPresent(accessToken ->
+            headerParams.add(HttpHeaders.AUTHORIZATION, "Bearer " + accessToken)
+        );
     }
 }

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

@@ -240,9 +240,18 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
      * @param accessToken Access token
      */
     public void setAccessToken(String accessToken) {
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Helper method to set the supplier of access tokens for OAuth2 authentication.
+     *
+     * @param tokenSupplier The supplier of bearer tokens
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
         for (Authentication auth : authentications.values()) {
             if (auth instanceof OAuth) {
-                ((OAuth) auth).setAccessToken(accessToken);
+                ((OAuth) auth).setAccessToken(tokenSupplier);
                 return;
             }
         }

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

@@ -1,24 +1,48 @@
 package org.openapitools.client.auth;
 
+import java.util.Optional;
+import java.util.function.Supplier;
 import org.springframework.http.HttpHeaders;
 import org.springframework.util.MultiValueMap;
 
+/**
+ * Provides support for RFC 6750 - Bearer Token usage for OAUTH 2.0 Authorization.
+ */
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.7.0-SNAPSHOT")
 public class OAuth implements Authentication {
-    private String accessToken;
+    private Supplier<String> tokenSupplier;
 
+    /**
+     * Returns the bearer token used for Authorization.
+     *
+     * @return The bearer token
+     */
     public String getAccessToken() {
-        return accessToken;
+        return tokenSupplier.get();
     }
 
+    /**
+     * Sets the bearer access token used for Authorization.
+     *
+     * @param bearerToken The bearer token to send in the Authorization header
+     */
     public void setAccessToken(String accessToken) {
-        this.accessToken = accessToken;
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Sets the supplier of bearer tokens used for Authorization.
+     *
+     * @param tokenSupplier The supplier of bearer tokens to send in the Authorization header
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
+        this.tokenSupplier = tokenSupplier;
     }
 
     @Override
     public void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams) {
-        if (accessToken != null) {
-            headerParams.add(HttpHeaders.AUTHORIZATION, "Bearer " + accessToken);
-        }
+        Optional.ofNullable(tokenSupplier).map(Supplier::get).ifPresent(accessToken ->
+            headerParams.add(HttpHeaders.AUTHORIZATION, "Bearer " + accessToken)
+        );
     }
 }

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

@@ -240,9 +240,18 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
      * @param accessToken Access token
      */
     public void setAccessToken(String accessToken) {
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Helper method to set the supplier of access tokens for OAuth2 authentication.
+     *
+     * @param tokenSupplier The supplier of bearer tokens
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
         for (Authentication auth : authentications.values()) {
             if (auth instanceof OAuth) {
-                ((OAuth) auth).setAccessToken(accessToken);
+                ((OAuth) auth).setAccessToken(tokenSupplier);
                 return;
             }
         }

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

@@ -1,24 +1,48 @@
 package org.openapitools.client.auth;
 
+import java.util.Optional;
+import java.util.function.Supplier;
 import org.springframework.http.HttpHeaders;
 import org.springframework.util.MultiValueMap;
 
+/**
+ * Provides support for RFC 6750 - Bearer Token usage for OAUTH 2.0 Authorization.
+ */
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.7.0-SNAPSHOT")
 public class OAuth implements Authentication {
-    private String accessToken;
+    private Supplier<String> tokenSupplier;
 
+    /**
+     * Returns the bearer token used for Authorization.
+     *
+     * @return The bearer token
+     */
     public String getAccessToken() {
-        return accessToken;
+        return tokenSupplier.get();
     }
 
+    /**
+     * Sets the bearer access token used for Authorization.
+     *
+     * @param bearerToken The bearer token to send in the Authorization header
+     */
     public void setAccessToken(String accessToken) {
-        this.accessToken = accessToken;
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Sets the supplier of bearer tokens used for Authorization.
+     *
+     * @param tokenSupplier The supplier of bearer tokens to send in the Authorization header
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
+        this.tokenSupplier = tokenSupplier;
     }
 
     @Override
     public void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams) {
-        if (accessToken != null) {
-            headerParams.add(HttpHeaders.AUTHORIZATION, "Bearer " + accessToken);
-        }
+        Optional.ofNullable(tokenSupplier).map(Supplier::get).ifPresent(accessToken ->
+            headerParams.add(HttpHeaders.AUTHORIZATION, "Bearer " + accessToken)
+        );
     }
 }

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

@@ -303,9 +303,18 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
      * @param accessToken Access token
      */
     public void setAccessToken(String accessToken) {
+        setAccessToken(() -> accessToken);
+    }
+
+    /**
+     * Helper method to set the supplier of access tokens for OAuth2 authentication.
+     *
+     * @param tokenSupplier The supplier of bearer tokens
+     */
+    public void setAccessToken(Supplier<String> tokenSupplier) {
         for (Authentication auth : authentications.values()) {
             if (auth instanceof OAuth) {
-                ((OAuth) auth).setAccessToken(accessToken);
+                ((OAuth) auth).setAccessToken(tokenSupplier);
                 return;
             }
         }