Allow configuring resource root of transport versions

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/transport/TransportVersionResourcesPlugin.java

@@ -61,8 +61,9 @@ public void apply(Project project) {
                 t.getDefinitionsDirectory().set(getDefinitionsDirectory(getResourcesDirectory(project)));
                 t.getManifestFile().set(project.getLayout().getBuildDirectory().file("generated-resources/manifest.txt"));
             });
+        String resourceRoot = TransportVersionUtils.getResourceRoot(project);
         project.getTasks().named(JavaPlugin.PROCESS_RESOURCES_TASK_NAME, Copy.class).configure(t -> {
-            t.into("transport/definitions", c -> c.from(generateManifestTask));
+            t.into(resourceRoot + "/definitions", c -> c.from(generateManifestTask));
         });
     }
 }

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/transport/TransportVersionUtils.java

@@ -50,7 +50,16 @@ static Directory getResourcesDirectory(Project project) {
         if (projectName == null) {
             projectName = ":server";
         }
+        var resourceRoot = getResourceRoot(project);
         Directory projectDir = project.project(projectName.toString()).getLayout().getProjectDirectory();
-        return projectDir.dir("src/main/resources/transport");
+        return projectDir.dir("src/main/resources/" + resourceRoot);
+    }
+
+    static String getResourceRoot(Project project) {
+        var resourceRoot = project.findProperty("org.elasticsearch.transport.resourceRoot");
+        if (resourceRoot == null) {
+            resourceRoot = "transport";
+        }
+        return resourceRoot.toString();
     }
 }

server/src/main/java/org/elasticsearch/TransportVersion.java

@@ -163,31 +163,32 @@ public static TransportVersion fromBufferedReader(
         }
     }
 
-    public static List<TransportVersion> collectFromInputStreams(
+    public static List<TransportVersion> collectFromResources(
         String component,
-        Function<String, InputStream> nameToStream,
+        String resourceRoot,
+        Function<String, InputStream> resourceLoader,
         String latestFileName
     ) {
         TransportVersion latest = parseFromBufferedReader(
             component,
-            "/transport/latest/" + latestFileName,
-            nameToStream,
+            resourceRoot + "/latest/" + latestFileName,
+            resourceLoader,
             (c, p, br) -> fromBufferedReader(c, p, true, false, br, Integer.MAX_VALUE)
         );
         if (latest != null) {
             List<String> versionRelativePaths = parseFromBufferedReader(
                 component,
-                "/transport/definitions/manifest.txt",
-                nameToStream,
+                resourceRoot + "/definitions/manifest.txt",
+                resourceLoader,
                 (c, p, br) -> br.lines().filter(line -> line.isBlank() == false).toList()
             );
             if (versionRelativePaths != null) {
                 List<TransportVersion> transportVersions = new ArrayList<>();
                 for (String versionRelativePath : versionRelativePaths) {
                     TransportVersion transportVersion = parseFromBufferedReader(
                         component,
-                        "/transport/definitions/" + versionRelativePath,
-                        nameToStream,
+                        resourceRoot + "/definitions/" + versionRelativePath,
+                        resourceLoader,
                         (c, p, br) -> fromBufferedReader(c, p, false, versionRelativePath.startsWith("named/"), br, latest.id())
                     );
                     if (transportVersion != null) {
@@ -426,8 +427,9 @@ private static class VersionsHolder {
         static {
             // collect all the transport versions from server and es modules/plugins (defined in server)
             List<TransportVersion> allVersions = new ArrayList<>(TransportVersions.DEFINED_VERSIONS);
-            List<TransportVersion> streamVersions = collectFromInputStreams(
+            List<TransportVersion> streamVersions = collectFromResources(
                 "<server>",
+                "/transport",
                 TransportVersion.class::getResourceAsStream,
                 Version.CURRENT.major + "." + Version.CURRENT.minor + ".csv"
             );