Some fixes for toReleaseVersion change elastic#112242 from the backport elastic#112280 (elastic#112284)

Author: thecoop

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

@@ -53,7 +53,7 @@ public static IntFunction<String> generateVersionsLookup(Class<?> versionContain
 
             NavigableMap<Integer, List<Version>> versions = new TreeMap<>();
             // add the current version id, which won't be in the csv
-            versions.put(current, List.of(Version.CURRENT));
+            versions.computeIfAbsent(current, k -> new ArrayList<>()).add(Version.CURRENT);
 
             try (BufferedReader reader = new BufferedReader(new InputStreamReader(versionsFile, StandardCharsets.UTF_8))) {
                 String line;

server/src/test/java/org/elasticsearch/TransportVersionTests.java

@@ -19,6 +19,7 @@
 import java.util.regex.Pattern;
 
 import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.endsWith;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.greaterThan;
 import static org.hamcrest.Matchers.is;
@@ -187,7 +188,7 @@ public void testCURRENTIsLatest() {
     }
 
     public void testToReleaseVersion() {
-        assertThat(TransportVersion.current().toReleaseVersion(), equalTo(Version.CURRENT.toString()));
+        assertThat(TransportVersion.current().toReleaseVersion(), endsWith(Version.CURRENT.toString()));
     }
 
     public void testToString() {