not invoke String.substring(int)

Question

  @Override
    protected void doFilterInternal(@NonNull HttpServletRequest request,
                                    @NonNull HttpServletResponse response,
                                    @NonNull FilterChain filterChain)
            throws ServletException, IOException {
        final String authHeader = request.getHeader("Authorization");
        final String userEmail;
        if (StringUtils.isEmpty(authHeader) || !StringUtils.startsWithIgnoreCase(authHeader,"Bearer")){
                 filterChain.doFilter(request, response);
        }

        final String jwt = authHeader.substring(7);
        userEmail = jwtUtil.extractUserName(jwt);
        if (StringUtils.isNotEmpty(userEmail)
                && SecurityContextHolder.getContext().getAuthentication() == null) {
            UserDetails userDetails = userService.userDetailsService().loadUserByUsername(userEmail);
            if (jwtUtil.isTokenValid(jwt, userDetails)){
                SecurityContext context = SecurityContextHolder.createEmptyContext();
                UsernamePasswordAuthenticationToken authToken = new UsernamePasswordAuthenticationToken(
                        userDetails, null,userDetails.getAuthorities());
                authToken.setDetails(new WebAuthenticationDetailsSource().buildDetails(request));
                context.setAuthentication(authToken);
                SecurityContextHolder.setContext(context);
            }

        }

        filterChain.doFilter(request, response);

    }

I want automatically add users passwords to database using postmans but the program works in Eclipse,but when I run the API in postman ı get this error. not invoke authHeader.substring(int) autheader is null