Add javadocs

Author: jormundur00

tests/tck-build-logic/src/main/java/org/graalvm/internal/tck/TestedVersionUpdaterTask.java

@@ -86,6 +86,19 @@ void run() throws IllegalStateException, IOException {
         Files.writeString(coordinatesMetadataIndex.toPath(), json, java.nio.charset.StandardCharsets.UTF_8);
     }
 
+    /**
+     * Handles pre-release versions when adding a new version to a metadata entry.
+     * <p>
+     * Rules applied by this method:
+     * <ul>
+     *     <li>If the newly added version is a full release (no pre-release label, or ends with ".Final"),
+     *         all old pre-releases of the same base version are removed from {@code testedVersions}.</li>
+     *     <li>If the newly added version is itself a pre-release, no versions are removed.</li>
+     *     <li>If the {@code metadataVersion} of the entry is a pre-release of the same base version,
+     *         it is updated to the new full release version and the corresponding directory is renamed.</li>
+     *     <li>Pre-release detection uses {@link #PRE_RELEASE_PATTERN} and respects ".Final" suffixes.</li>
+     * </ul>
+     */
     private MetadataVersionsIndexEntry handlePreReleases(MetadataVersionsIndexEntry entry, String newVersion, Path baseDir) throws IOException {
         // strip .Final if present
         String cleanedNewVersion = FINAL_PATTERN.matcher(newVersion).replaceAll("");