Allow configure manifest file when loading transport versions

This commit adds the manifest file name as an argument when loading
transport versions from resource files. This allows multiple manifests
to exist on the test classpath at once, eg in serverless.

Author: rjernst

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

@@ -163,22 +163,23 @@ public static TransportVersion fromBufferedReader(
         }
     }
 
-    public static List<TransportVersion> collectFromInputStreams(
+    public static List<TransportVersion> collectFromResources(
         String component,
-        Function<String, InputStream> nameToStream,
+        Function<String, InputStream> resourceLoader,
+        String manifestFileName,
         String latestFileName
     ) {
         TransportVersion latest = parseFromBufferedReader(
             component,
             "/transport/latest/" + latestFileName,
-            nameToStream,
+            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,
+                "/transport/definitions/" + manifestFileName,
+                resourceLoader,
                 (c, p, br) -> br.lines().filter(line -> line.isBlank() == false).toList()
             );
             if (versionRelativePaths != null) {
@@ -187,7 +188,7 @@ public static List<TransportVersion> collectFromInputStreams(
                     TransportVersion transportVersion = parseFromBufferedReader(
                         component,
                         "/transport/definitions/" + versionRelativePath,
-                        nameToStream,
+                        resourceLoader,
                         (c, p, br) -> fromBufferedReader(c, p, false, versionRelativePath.startsWith("named/"), br, latest.id())
                     );
                     if (transportVersion != null) {
@@ -426,9 +427,10 @@ 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>",
                 TransportVersion.class::getResourceAsStream,
+                "manifest.txt",
                 Version.CURRENT.major + "." + Version.CURRENT.minor + ".csv"
             );
             Map<String, TransportVersion> allVersionsByName = streamVersions.stream()