fix: replace deprecated returnResource() and add JedisPool shutdown hook (#1188)

Two resource management issues fixed:
1. returnConnection() used jedisPool.returnResource() which has been
   deprecated since Jedis 3.0. Replaced with jedis.close() which correctly
   returns healthy connections to the pool and closes broken ones.
2. JedisPool was never closed, leaving open connections and background
   threads after process exit. Added closePool() and a JVM shutdown hook
   to ensure the pool is always properly released on shutdown.

Co-authored-by: Claude <claude@anthropic.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: pallakartheekreddy

platform-core/platform-cache/src/main/scala/org/sunbird/cache/util/RedisConnector.scala

@@ -1,6 +1,7 @@
 package org.sunbird.cache.util
 
 import org.sunbird.common.Platform
+import org.sunbird.telemetry.logger.TelemetryManager
 import redis.clients.jedis.{Jedis, JedisPool, JedisPoolConfig}
 
 /**
@@ -14,6 +15,8 @@ trait RedisConnector {
 	private val INDEX = Platform.getInteger("redis.dbIndex", 0)
 	private val jedisPool: JedisPool = new JedisPool(getConfig(), HOST, PORT)
 
+	registerShutdownHook()
+
 	/**
 	 * This Method Returns a connection object from connection pool.
 	 *
@@ -28,21 +31,45 @@ trait RedisConnector {
 	}
 
 	/**
-	 * This Method takes a connection object and put it back to pool.
+	 * This Method takes a connection object and returns it to pool.
+	 * Uses jedis.close() which is the modern, non-deprecated approach
+	 * and correctly returns the connection to the pool (or closes it if broken).
 	 *
 	 * @param jedis
 	 */
 	protected def returnConnection(jedis: Jedis): Unit = {
-		try if (null != jedis) jedisPool.returnResource(jedis)
-		catch {
-			case e: Exception => throw e
+		if (null != jedis) {
+			try jedis.close()
+			catch {
+				case e: Exception => TelemetryManager.error("Error returning Redis connection to pool: " + e.getMessage, e)
+			}
+		}
+	}
+
+	/**
+	 * Closes the JedisPool, releasing all connections.
+	 * Called automatically via the JVM shutdown hook.
+	 */
+	def closePool(): Unit = {
+		if (jedisPool != null && !jedisPool.isClosed) {
+			try jedisPool.close()
+			catch {
+				case e: Exception => TelemetryManager.error("Error closing JedisPool: " + e.getMessage, e)
+			}
 		}
 	}
 
+	private def registerShutdownHook(): Unit = {
+		Runtime.getRuntime.addShutdownHook(new Thread(() => {
+			TelemetryManager.log("Shutting down RedisConnector — closing connection pool")
+			closePool()
+		}))
+	}
+
 	private def getConfig(): JedisPoolConfig = {
 		val config: JedisPoolConfig = new JedisPoolConfig()
 		config.setMaxTotal(MAX_CONNECTIONS)
-		config.setBlockWhenExhausted(true);
+		config.setBlockWhenExhausted(true)
 		config
 	}
 }