How to properly filter span by sampling

[blephy]

I have an API that has 3 endpoints on which I would not like to send any span to my collector.

I have designed a custom SpanSampler to filter them, but this is not working as expected.

Could you please help me to review my implementation ?

// conventions/conventions.ts
const HTTP_METHOD_BLACKLIST = ['HEAD', 'OPTIONS', 'TRACE', 'CONNECT'];
const HTTP_ROUTE_BLACKLIST = ['/liveness', '/readyness', '/metrics'];

export { HTTP_METHOD_BLACKLIST, HTTP_ROUTE_BLACKLIST };

import { SamplingDecision, TraceIdRatioBasedSampler } from '@opentelemetry/sdk-trace-node';
import { ATTR_HTTP_REQUEST_METHOD, ATTR_HTTP_ROUTE } from '@opentelemetry/semantic-conventions';

import { HTTP_METHOD_BLACKLIST, HTTP_ROUTE_BLACKLIST } from '../conventions/conventions.js';

import type { Attributes, AttributeValue, Context, Link, SpanKind } from '@opentelemetry/api';
import type { Sampler, SamplingResult } from '@opentelemetry/sdk-trace-node';

class CustomSampler extends TraceIdRatioBasedSampler implements Sampler {
  public readonly excludeHttpMethods = HTTP_METHOD_BLACKLIST;

  public readonly excludeHttpRoutes = HTTP_ROUTE_BLACKLIST;

  // @ts-expect-error -- this is obvious with TS ! We can do it for sure
  // eslint-disable-next-line max-params
  public override shouldSample(
    context: Context,
    traceId: string,
    _spanName: string,
    _spanKind: SpanKind,
    attributes: Attributes,
    _links: Array<Link>,
  ): SamplingResult {
    const radioSampleDecision: SamplingResult = super.shouldSample(context, traceId);

    if (radioSampleDecision.decision === SamplingDecision.NOT_RECORD) {
      return radioSampleDecision;
    }

    const maybeSpanHttpMethod: AttributeValue | undefined =
      attributes['http.method'] ?? attributes[ATTR_HTTP_REQUEST_METHOD];
    const maybeSpanHttpRoute: AttributeValue | undefined =
      attributes['http.route'] ?? attributes[ATTR_HTTP_ROUTE];

    const normalizedHttpMethod = maybeSpanHttpMethod?.toString().toUpperCase() ?? 'GET';
    const normalizedHttpRoute = maybeSpanHttpRoute?.toString().toLowerCase() ?? '/';

    if (this.excludeHttpMethods.includes(normalizedHttpMethod)) {
      return {
        ...radioSampleDecision,
        decision: SamplingDecision.NOT_RECORD,
      };
    }

    if (this.excludeHttpRoutes.includes(normalizedHttpRoute)) {
      return {
        ...radioSampleDecision,
        decision: SamplingDecision.NOT_RECORD,
      };
    }

    return radioSampleDecision;
  }
}

export { CustomSampler };

My sampler is triggered, and my decision are returned, but SamplingDecision.NOT_RECORD is not doing anything, span are still sent on my collector

What did i missed ?