Exposing getSchemaVersion in the client by making it public. (#3744)

* Exposing getSchemaVersion in the client by making it public.

* Implemented getSchemaVersion in TopicMessageImpl.java

* Changed the release version

pulsar-client-api/src/main/java/org/apache/pulsar/client/api/Message.java

@@ -180,4 +180,11 @@ public interface Message<T> {
      * @return message redelivery count
      */
     int getRedeliveryCount();
+
+    /**
+     * Get schema version of the message.
+     * @since 2.4.0
+     * @return Schema version of the message if the message is produced with schema otherwise null.
+     */
+    byte[] getSchemaVersion();
 }

pulsar-client/src/main/java/org/apache/pulsar/client/impl/MessageImpl.java

@@ -228,7 +228,8 @@ public byte[] getData() {
         }
     }
 
-    private byte[] getSchemaVersion() {
+    @Override
+    public byte[] getSchemaVersion() {
         if (msgMetadataBuilder.hasSchemaVersion()) {
             return msgMetadataBuilder.getSchemaVersion().toByteArray();
         } else {

pulsar-client/src/main/java/org/apache/pulsar/client/impl/TopicMessageImpl.java

@@ -143,6 +143,11 @@ public int getRedeliveryCount() {
         return msg.getRedeliveryCount();
     }
 
+    @Override
+    public byte[] getSchemaVersion() {
+        return msg.getSchemaVersion();
+    }
+
     public Message<T> getMessage() {
         return msg;
     }