feat: Support additional request parameters for 3LO

google-oauth-client/src/main/java/com/google/api/client/auth/oauth2/AuthorizationCodeFlow.java

@@ -112,6 +112,9 @@ public class AuthorizationCodeFlow {
   /** Refresh listeners provided by the client. */
   private final Collection<CredentialRefreshListener> refreshListeners;
 
+  /** Additional parameters to pass to authorization url. */
+  private final Map<String, String> additionalParameters;
+
   /**
    * @param method method of presenting the access token to the resource server (for example {@link
    *     BearerToken#authorizationHeaderAccessMethod})
@@ -156,6 +159,7 @@ protected AuthorizationCodeFlow(Builder builder) {
     clientId = Preconditions.checkNotNull(builder.clientId);
     authorizationServerEncodedUrl =
         Preconditions.checkNotNull(builder.authorizationServerEncodedUrl);
+    additionalParameters = builder.additionalParameters;
     requestInitializer = builder.requestInitializer;
     credentialStore = builder.credentialStore;
     credentialDataStore = builder.credentialDataStore;
@@ -192,6 +196,11 @@ public AuthorizationCodeRequestUrl newAuthorizationUrl() {
       url.setCodeChallenge(pkce.getChallenge());
       url.setCodeChallengeMethod(pkce.getChallengeMethod());
     }
+    if (additionalParameters != null) {
+      for (Map.Entry<String, String> entry : additionalParameters.entrySet()) {
+        url.put(entry.getKey(), entry.getValue());
+      }
+    }
     return url;
   }
 
@@ -549,6 +558,9 @@ public static class Builder {
     /** Refresh listeners provided by the client. */
     Collection<CredentialRefreshListener> refreshListeners = Lists.newArrayList();
 
+    /** Additional authorization url parameters provided by the client * */
+    Map<String, String> additionalParameters;
+
     /**
      * @param method method of presenting the access token to the resource server (for example
      *     {@link BearerToken#authorizationHeaderAccessMethod})
@@ -575,6 +587,7 @@ public Builder(
       setClientAuthentication(clientAuthentication);
       setClientId(clientId);
       setAuthorizationServerEncodedUrl(authorizationServerEncodedUrl);
+      setAdditionalParameters(Collections.<String, String>emptyMap());
     }
 
     /** Returns a new instance of an authorization code flow based on this builder. */
@@ -717,6 +730,19 @@ public Builder setAuthorizationServerEncodedUrl(String authorizationServerEncode
       return this;
     }
 
+    /**
+     * Sets the additional url parameters.
+     *
+     * <p>Overriding is only supported for the purpose of calling the super implementation and
+     * changing the return type, but nothing else.
+     *
+     * @since 1.11
+     */
+    public Builder setAdditionalParameters(Map<String, String> additionalParameters) {
+      this.additionalParameters = Preconditions.checkNotNull(additionalParameters);
+      return this;
+    }
+
     /**
      * {@link Beta} <br>
      * Returns the credential persistence store or {@code null} for none.

google-oauth-client/src/test/java/com/google/api/client/auth/oauth2/AuthorizationCodeFlowTest.java

@@ -22,7 +22,9 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Map;
 import java.util.Set;
 
 /**
@@ -154,4 +156,24 @@ public void testPKCE() {
     assertTrue(methods.contains(url.getCodeChallengeMethod().toLowerCase()));
     assertTrue(url.getCodeChallenge().length() > 0);
   }
+
+  public void testAdditionalParameters() {
+    Map<String, String> testMap = new HashMap<>();
+    testMap.put("key", "value");
+    AuthorizationCodeFlow flow =
+        new AuthorizationCodeFlow.Builder(
+                BearerToken.queryParameterAccessMethod(),
+                new AccessTokenTransport(),
+                new GsonFactory(),
+                TOKEN_SERVER_URL,
+                new BasicAuthentication(CLIENT_ID, CLIENT_SECRET),
+                CLIENT_ID,
+                "https://example.com")
+            .setAdditionalParameters(testMap)
+            .build();
+
+    AuthorizationCodeRequestUrl url = flow.newAuthorizationUrl();
+    String urlString = url.build();
+    assertTrue(urlString.contains("key=value"));
+  }
 }