Token Exception - Invalid Check sum is the error I ma getting from the response.

Hi please find the Cod base that I'm attaching

I have gone through the threads, also i have refresh the build and made sure the request and SHA256value is generated using the right key .
my call back function is
@RequestMapping(path = "login/kite/callback", produces = "application/json; charset=UTF-8",method = RequestMethod.GET)
@Override
public void loginCallBack(@RequestParam("request_token")String access_token) {
System.out.println("call back obtained:"+access_token);
KiteConnect kiteConnect = new KiteConnect("XXXXX");
try {
User user = kiteConnect.generateSession(access_token,"XXXXXX");
kiteConnect.setAccessToken(user.accessToken);
kiteConnect.setPublicToken(user.publicToken);
} catch (KiteException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

I am getting the request_token and When I call the generate session I ma getting the issue of Token exception.
Attached is the error log.

com.zerodhatech.kiteconnect.kitehttp.exceptions.TokenException
at com.zerodhatech.kiteconnect.kitehttp.KiteResponseHandler.dealWithException(KiteResponseHandler.java:48)
at com.zerodhatech.kiteconnect.kitehttp.KiteResponseHandler.handle(KiteResponseHandler.java:20)
at com.zerodhatech.kiteconnect.kitehttp.KiteRequestHandler.postRequest(KiteRequestHandler.java:85)
at com.zerodhatech.kiteconnect.KiteConnect.generateSession(KiteConnect.java:189)
at com.trade.algo.login.KiteLogin.loginCallBack(KiteLogin.java:56)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:879)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:793)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:634)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)

please help to resolve.