ZOOKEEPER-4962: Export bound client port for ZooKeeperServerEmbedded

Since, `ZooKeeperServerEmbedded` could bind to port 0 and get unused
port from system. It would be good to export the bound client port in
addition to `getConnectionString`.

Author: kezhuw

zookeeper-server/src/main/java/org/apache/zookeeper/server/ZooKeeperServerMain.java

@@ -242,15 +242,13 @@ ServerCnxnFactory getSecureCnxnFactory() {
         return secureCnxnFactory;
     }
 
-    // VisibleForTesting
     public int getClientPort() {
         if (cnxnFactory != null) {
             return cnxnFactory.getLocalPort();
         }
         return 0;
     }
 
-    // VisibleForTesting
     public int getSecureClientPort() {
         if (secureCnxnFactory != null) {
             return secureCnxnFactory.getLocalPort();

zookeeper-server/src/main/java/org/apache/zookeeper/server/embedded/ZooKeeperServerEmbedded.java

@@ -116,6 +116,16 @@ static ZookKeeperServerEmbeddedBuilder builder() {
      */
     void start(long startupTimeout) throws Exception;
 
+    /**
+     * Get client port for no secure connection.
+     */
+    int getClientPort();
+
+    /**
+     * Get client port for secure connection.
+     */
+    int getSecureClientPort();
+
     /**
      * Get a connection string useful for the client.
      * @return the connection string

zookeeper-server/src/main/java/org/apache/zookeeper/server/embedded/ZooKeeperServerEmbeddedImpl.java

@@ -190,6 +190,16 @@ public void run() {
         }
     }
 
+    @Override
+    public int getClientPort() {
+        return boundClientPort;
+    }
+
+    @Override
+    public int getSecureClientPort() {
+        return boundSecureClientPort;
+    }
+
     @Override
     public String getConnectionString() {
         return prettifyConnectionString(config.getClientPortAddress(), boundClientPort);