Spring Boot with AWS IoT api's connection getting error 403 forbidden

I am creating signature using AWS doc sample:

static byte[] HmacSHA256(String data, byte[] key) throws Exception {
	    String algorithm="HmacSHA256";
	    Mac mac = Mac.getInstance(algorithm);
	    mac.init(new SecretKeySpec(key, algorithm));
	    return mac.doFinal(data.getBytes("UTF-8"));
	}

static byte[] getSignatureKey(String key, String dateStamp, String regionName, String serviceName) throws Exception {
	    byte[] kSecret = ("AWS4" + key).getBytes("UTF-8");
	    byte[] kDate = HmacSHA256(dateStamp, kSecret);
	    byte[] kRegion = HmacSHA256(regionName, kDate);
	    byte[] kService = HmacSHA256(serviceName, kRegion);
	    byte[] kSigning = HmacSHA256("aws4_request", kService);
	    return kSigning;
	}


String url = "https://iot.us-east-1.amazonaws.com/things?thingTypeName={thingTypeName}";

	@RequestMapping(value = "/things",produces=MediaType.APPLICATION_JSON_VALUE)
	public void getThingLists() throws Exception {
		 SimpleDateFormat f = new SimpleDateFormat("yyyyMMdd'T'HHmmss'Z'");
		 String date=f.format(new Date());
		    byte[] signature1 = getSignatureKey(secretKey, date, regionName, serviceName);
		    String signature=Hex.encodeHexString(signature1);
		    //String s = Base64.getEncoder().encodeToString(signature1);
		    System.out.println("Signature : " + signature);
		    String str="Signature="+signature ;
			str="AWS4-HMAC-SHA256 Credential=AKIA4XDJYZKLHCNVHNBA/20200724/us-east-1/execute-api/aws4_request, SignedHeaders=host;x-amz-date,"+str ;
			System.out.println(str);
		HttpHeaders headers = new HttpHeaders();
		headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
		headers.add("Content-Type", MediaType.APPLICATION_JSON_VALUE);
		headers.add("user-agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36");
		headers.add("x-amz-date", date);
		headers.add("Authorization",str);
		HttpEntity<String> entity = new HttpEntity<String>(headers);
        // Send request with GET method, and Headers.
        ResponseEntity<String> response = restTemplate.exchange(url,
                HttpMethod.GET, entity, String.class,"SmartLed001");
		//return restTemplate.exchange(url, HttpMethod.GET, entity, String.class,"SmartLed001").getBody();
		 String result = response.getBody();
	        System.out.println(result);
	}

The error I am getting is:

org.springframework.web.client.HttpClientErrorException$Forbidden: 403 Forbidden
	at org.springframework.web.client.HttpClientErrorException.create(HttpClientErrorException.java:83)

How can I solve this?