ThreadLocal is returning null, even after being set in HandlerInterceptor - spring

Question

ThreadLocal in being set in HandlerInterceptor for each request, but sometimes it is returning null instead of the expected value, when accessing in the service layer.
As stated by docs ThreadLocal objects are thread safe and are local to a single request thread. So even if multiple requests are setting/clearing it, it will only get set/cleared for that particular request thread and not impact the request threads.
But 1-2 times(not able to reproduce now, even with lot of logging statements) in debug mode, I encounter that the ThreadLocal to be null in the service layer(thus got a NullPointerException), even though it should not be as it's being set in the HandlerInceptor which always hits first before the controller layer in spring-boot.
Is below ThreadLocal code really thread-safe, when multiple request threads access it simultaneously.
Is it possible that Interceptor is executed in one Thread and controller executes in another thread and somehow controller thread executes first before interceptor sets the values in ThreadLocal.
Code :
ThreadLocal.class
#Component
public class ThreadLocalUtil {
private static final ThreadLocal<ConstantsConfig> constantsConfig = new InheritableThreadLocal<>();
public static ConstantsConfig getConstantsConfig() {
return constantsConfig.get();
}
public static void setConstantsConfig(ConstantsConfig config) {
constantsConfig.set(config);
}
public static void clearConstantsConfig() {
constantsConfig.remove();
}
}
HandlerInceptor.class
public class RequestInterceptor implements HandlerInterceptor {
#Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
if (request.getRequestURI().equals("/health")) {
return true;
}
// we are always setting ThreadLocal, before accessing it in service layer.
setConstants(request);
logThreadLocal();
return true;
}
private void setConstants(HttpServletRequest request) {
ThreadLocalUtil.setConstantsConfig(BeanUtil.getBean(ImplConstantsConfig.class))
}
#Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
throws Exception {
if (request.getRequestURI().equals("/health")) {
return;
}
ThreadLocalUtil.clearConstantsConfig();
}
AccessorService.class
// accessed in multiple service classes for 1 request/response cycle.
ThreadLocalUtil.getConstantsConfig().getProperty1()
ThreadLocalUtil.getConstantsConfig().getProperty2()