revert ? Not here... add it to `CipherSuiteConverter ` sorry, didn't understand this point. Failure which I see in the last build is : 
```
Failures: 
2021-09-04T19:13:09.0782449Z [ERROR]   JdkOpenSslEngineInteroptTest.testMutualAuthDiffCerts:78->SSLEngineTest.testMutualAuthDiffCerts:633->SSLEngineTest.runTest:1267->SSLEngineTest.writeAndVerifyReceived:1296 expected: <true> but was: <false>
```

But why we are adding `@UnstableApi` to `CipherSuitesConverter` class?
 I see the point after reading the documentation about it. updated.
ability to CipherSuitesConverter outside of the io.netty.handler.ssl
In our use case, we are required to convert the java cipher suites are required to be converted to Openssl. I found that netty already has a `CipherSuitesConverter`. As we are already using netty, we could have reused the class if it was not made the package private. IMO it would be no harm if we make it public to be used for the project using netty already.

I will raise a pull request for the same.
handler/src/main/java/io/netty/handler/ssl/CipherSuiteConverter.java
handler/src/main/java/io/netty/handler/ssl/CipherSuiteConverter.java
diff --git a/handler/src/main/java/io/netty/handler/ssl/CipherSuiteConverter.java b/handler/src/main/java/io/netty/handler/ssl/CipherSuiteConverter.java
index 2dd81371adb..a9ac8307c1d 100644
--- a/handler/src/main/java/io/netty/handler/ssl/CipherSuiteConverter.java
+++ b/handler/src/main/java/io/netty/handler/ssl/CipherSuiteConverter.java
@@ -17,6 +17,7 @@
 package io.netty.handler.ssl;
 
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.UnstableApi;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 
@@ -34,7 +35,8 @@
  *
  * @see <a href="https://en.wikipedia.org/wiki/Cipher_suite">Wikipedia page about cipher suite</a>
  */
-final class CipherSuiteConverter {
+@UnstableApi
+public final class CipherSuiteConverter {
 
     private static final InternalLogger logger = InternalLoggerFactory.getInstance(CipherSuiteConverter.class);
 
@@ -150,7 +152,7 @@ static boolean isO2JCached(String key, String protocol, String value) {
      *
      * @return {@code null} if the conversion has failed
      */
-    static String toOpenSsl(String javaCipherSuite, boolean boringSSL) {
+    public static String toOpenSsl(String javaCipherSuite, boolean boringSSL) {
         String converted = j2o.get(javaCipherSuite);
         if (converted != null) {
             return converted;
@@ -279,7 +281,7 @@ private static String toOpenSslHmacAlgo(String hmacAlgo) {
      * @param protocol The cryptographic protocol (i.e. SSL, TLS, ...).
      * @return The translated cipher suite name according to java conventions. This will not be {@code null}.
      */
-    static String toJava(String openSslCipherSuite, String protocol) {
+    public static String toJava(String openSslCipherSuite, String protocol) {
         Map<String, String> p2j = o2j.get(openSslCipherSuite);
         if (p2j == null) {
             p2j = cacheFromOpenSsl(openSslCipherSuite);
