#vulnerable code 
                                public void register(JsonProvider jsonProvider) {
        this.registeredJsonProvider = Objects.requireNonNull(jsonProvider);
        logger.debug(() -> "Set json provider to " + jsonProvider.getClass().getName());
    } 
                            #location 3 
                            #vulnerability type INTERFACE_NOT_THREAD_SAFE
#fixed code
                                public void register(JsonProvider jsonProvider) {
        this.registeredJsonProvider = Objects.requireNonNull(jsonProvider);
    }