Spring Security - 401 Unauthorized for token end point (/oauth/token)

Question

I am trying to implement oauth2 to secure all my API's but i'm getting 401 unauthorized when trying to get the token from end point /oauth/token.

I tried with following code. Below are my configurations

Authorization Server Configuration

@Configuration
@EnableAuthorizationServer
public class AuthorizationServerConfig extends AuthorizationServerConfigurerAdapter {

    @Autowired
    private AuthenticationManager authenticationManager;

    @Override
    public void configure(final AuthorizationServerEndpointsConfigurer endpoints) {
        endpoints.tokenStore(tokenStore()).authenticationManager(authenticationManager);
    }

    @Bean
    public TokenStore tokenStore() {
        return new InMemoryTokenStore();
    }
}

Resource Server Configuration

@Configuration
@EnableResourceServer
public class GatewayConfiguration extends ResourceServerConfigurerAdapter {
    @Override
    public void configure(final HttpSecurity http) throws Exception {
    http.csrf().disable().anonymous().and().authorizeRequests()
          .antMatchers(HttpMethod.OPTIONS,"/oauth/token").permitAll()
          .anyRequest().authenticated().and().cors().disable();
    }
}

Security Configuration

@Configuration
@EnableWebSecurity
@EnableGlobalMethodSecurity(prePostEnabled = true)
public class ServiceConfig extends WebSecurityConfigurerAdapter {


    @Bean
    public UserDetailsService userDetailsService() {
        return new UserDetailsServiceImp();
    };


    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.userDetailsService(userDetailsService());
    }

    @Bean
    @Override
    public AuthenticationManager authenticationManagerBean() throws Exception {
        return super.authenticationManagerBean();
    }

}

CorsFilter Configuration

@Configuration
@Order(Ordered.HIGHEST_PRECEDENCE)
public class SimpleCorsFilter implements Filter {

    public SimpleCorsFilter() {
    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletResponse response = (HttpServletResponse) res;
        HttpServletRequest request = (HttpServletRequest) req;
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE, PUT");
        response.setHeader("Access-Control-Max-Age", "3600");
        response.setHeader("Access-Control-Allow-Headers", "x-requested-with, authorization,Content-Type,Authorization, credential, X-XSRF-TOKEN");

        if ("OPTIONS".equalsIgnoreCase(request.getMethod())) {
            response.setStatus(HttpServletResponse.SC_OK);
        } else {
            chain.doFilter(req, res);
        }
    }

    @Override
    public void init(FilterConfig filterConfig) {
    }

    @Override
    public void destroy() {
    }
}

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