private void callback(final SummaryWithCallback.Callback callback) {
    labelledCallbackData
        .values()
        .forEach(
            callbackData -> {
              final var externalSummary = callbackData.summarySupplier().get();
              final var quantilesBuilder = Quantiles.builder();
              externalSummary.quantiles().stream()
                  .map(pq -> new Quantile(pq.quantile(), pq.value()))
                  .forEach(quantilesBuilder::quantile);
              callback.call(
                  externalSummary.count(), externalSummary.sum(), quantilesBuilder.build());
            });
  }
Map label values with the collector callback data
metrics/core/src/main/java/org/hyperledger/besu/metrics/prometheus/PrometheusSuppliedSummary.java