Skip BOM download when version contains unresolved placeholders (#6674)

* Add failing test for mavenBom with unresolved Gradle variable

Reproduces IllegalArgumentException when RemoveRedundantDependencyVersions
encounters a mavenBom dependency that uses a Gradle variable reference like
${springCloudVersion}. The unresolved placeholder is passed to
MavenPomDownloader.download() which fails in URI.create().

* Skip BOM download when version contains unresolved placeholders

When a mavenBom entry in the Spring dependency-management plugin uses a
Gradle variable (e.g. ${springCloudVersion}), the version is stored as
a literal placeholder string. Passing this to MavenPomDownloader.download()
causes IllegalArgumentException from URI.create() because ${ is not valid
in a URI path.

Skip the download attempt when the version contains unresolved ${}
placeholders, consistent with how the recipe already handles missing
versions.

Author: Jenson3210

rewrite-gradle/src/main/java/org/openrewrite/gradle/RemoveRedundantDependencyVersions.java

@@ -155,9 +155,13 @@ public J.MethodInvocation visitMethodInvocation(J.MethodInvocation method, Execu
                                         J.MethodInvocation m = super.visitMethodInvocation(method, ctx);
                                         new SpringDependencyManagementPluginEntry.Matcher().get(getCursor()).ifPresent(entry -> entry.getArtifacts().forEach(artifact -> {
                                             if ("mavenBom".equals(method.getSimpleName())) {
+                                                String version = entry.getVersion();
+                                                if (version == null || version.contains("${")) {
+                                                    return;
+                                                }
                                                 MavenPomDownloader mpd = new MavenPomDownloader(ctx);
                                                 try {
-                                                    ResolvedPom platformPom = mpd.download(new GroupArtifactVersion(entry.getGroup(), artifact, entry.getVersion()), null, null, gp.getMavenRepositories())
+                                                    ResolvedPom platformPom = mpd.download(new GroupArtifactVersion(entry.getGroup(), artifact, version), null, null, gp.getMavenRepositories())
                                                             .resolve(emptyList(), mpd, ctx);
                                                     platformPom.getDependencyManagement().stream()
                                                             .filter(managedVersion -> managedVersion.getVersion() != null)

rewrite-gradle/src/test/java/org/openrewrite/gradle/RemoveRedundantDependencyVersionsTest.java

@@ -1017,4 +1017,65 @@ void webfluxGTE() {
           )
         );
     }
+
+    @Test
+    void mavenBomWithUnresolvedVariable() {
+        rewriteRun(
+          spec -> spec.recipe(new RemoveRedundantDependencyVersions(null, null, RemoveRedundantDependencyVersions.Comparator.GTE)),
+          buildGradle(
+            """
+              plugins {
+                  id "java"
+                  id("org.springframework.boot") version "3.5.6"
+                  id("io.spring.dependency-management") version "1.1.7"
+              }
+
+              ext {
+                  springCloudVersion = '2024.0.1'
+              }
+
+              repositories {
+                  mavenCentral()
+              }
+
+              dependencyManagement {
+                  imports {
+                      mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
+                  }
+              }
+
+              dependencies {
+                  implementation('org.springframework.boot:spring-boot')
+                  implementation("org.apache.commons:commons-lang3:3.14.0")
+              }
+              """,
+            """
+              plugins {
+                  id "java"
+                  id("org.springframework.boot") version "3.5.6"
+                  id("io.spring.dependency-management") version "1.1.7"
+              }
+
+              ext {
+                  springCloudVersion = '2024.0.1'
+              }
+
+              repositories {
+                  mavenCentral()
+              }
+
+              dependencyManagement {
+                  imports {
+                      mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
+                  }
+              }
+
+              dependencies {
+                  implementation('org.springframework.boot:spring-boot')
+                  implementation("org.apache.commons:commons-lang3")
+              }
+              """
+          )
+        );
+    }
 }