NPE in HttpClientBuilder addExecInterceptorFirst and addExecInterceptorLast

HttpClients.custom().addExecInterceptorFirst("name", (ExecChainHandler) (request, scope, chain) -> null).build();

HttpClients.custom().addExecInterceptorLast("name", (ExecChainHandler) (request, scope, chain) -> null).build();

if (execInterceptors == null) {
    execInterceptors = new LinkedList<>();
}