title: What it means in simplified language
body: <pre><code>HTTP Status 500 - Request processing failed; nested exception is java.lang.NullPointerException
  
  type Exception report
  
  message Request processing failed; nested exception is java.lang.NullPointerException
  
  description The server encountered an internal error that prevented it from fulfilling this request.
  
  exception
  
  org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
      org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:973)
      org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
      org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
      org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
      org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
      org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
  root cause
  
  java.lang.NullPointerException
      com.kulv.pubUser.controller.OAuthController.getAccessToken(OAuthController.java:61)
      sun.reflect.GeneratedMethodAccessor127.invoke(Unknown Source)
      sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      java.lang.reflect.Method.invoke(Method.java:606)
      org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
      org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
      org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
      org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:781)
      org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:721)
      org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
      org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:943)
      org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:877)
      org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
      org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
      org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
      org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
      org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
      org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
  note The full stack trace of the root cause is available in the Apache Tomcat/7.0.53 logs.
  
  Apache Tomcat/7.0.53
  </code></pre>
  
  <p>Thank for answering .... I'm not familiar with informatic languages</p>