added log tracing classes

src/main/java/com/billpaymentservice/bbps/util/Helper.java

@@ -1,5 +1,6 @@
 package com.billpaymentservice.bbps.util;
 
+import java.security.SecureRandom;
 import java.util.function.Function;
 
 import org.slf4j.Logger;
@@ -19,6 +20,9 @@ import com.billpaymentservice.bbps.repository.MerchantRepository;
 public class Helper {
 
 	private static final Logger LOGGER = LoggerFactory.getLogger(Helper.class);
+	
+	private static final String CHARACTERS = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+	private static final SecureRandom secureRandom = new SecureRandom();
 
 	@Autowired
 	private MerchantRepository merchantRegisterRepo;
@@ -111,4 +115,14 @@ public class Helper {
 //	    LOGGER.info("Merchant is valid and active for MID: {}", requestModel.getMid());
 	    return "Valid";  // Success message
 	}
+	
+	public static String generateTxnId(int n) {
+		StringBuilder sb = new StringBuilder(n);
+
+		for (int i = 0; i < n; i++) {
+			int index = secureRandom.nextInt(CHARACTERS.length());
+			sb.append(CHARACTERS.charAt(index));
+		}
+		return sb.toString(); // Prefix
+	}
 }