Limit name-based repo duplicate check to URL-less repositories (#7245)

The name-based fallback added in #7230 incorrectly blocks adding a
second `maven {}` or `ivy {}` repository with a different URL, since
it only checks the method name. Gate the check on `url == null` so it
only applies to uniquely-named repositories like `gradlePluginPortal`,
`mavenCentral`, `mavenLocal`, and `google`.

Author: pstreef

rewrite-gradle/src/main/java/org/openrewrite/gradle/plugins/AddSettingsPluginRepository.java

@@ -197,7 +197,7 @@ private Statement addRepoToRepositoriesBlock(Statement statement, J pluginManage
                 }
                 J.MethodInvocation repoToAdd = extractRepository(pluginManagement);
 
-                if (repoAlreadyExists(repos, repoToAdd.getSimpleName())) {
+                if (url == null && repoAlreadyExists(repos, repoToAdd.getSimpleName())) {
                     return statement;
                 }
 

rewrite-gradle/src/test/java/org/openrewrite/gradle/plugins/AddSettingsPluginRepositoryTest.java

@@ -642,6 +642,37 @@ void skipWhenExistsGradlePluginPortalWithOtherReposKtsWithoutTypeAttribution() {
         );
     }
 
+    @Test
+    void addSecondMavenRepoKts() {
+        rewriteRun(
+          spec -> spec.recipe(new AddSettingsPluginRepository("maven", "https://repo.spring.io"))
+            .expectedCyclesThatMakeChanges(1).cycles(3),
+          settingsGradleKts(
+            """
+              pluginManagement {
+                  repositories {
+                      maven {
+                          url = uri("https://repo.example.com/releases")
+                      }
+                  }
+              }
+              """,
+            """
+              pluginManagement {
+                  repositories {
+                      maven {
+                          url = uri("https://repo.example.com/releases")
+                      }
+                      maven {
+                          url = uri("https://repo.spring.io")
+                      }
+                  }
+              }
+              """
+          )
+        );
+    }
+
     @Test
     void addToExistingPluginManagementWithPluginsBlockKts() {
         rewriteRun(