Merge branch '1.13.x'

docs/modules/ROOT/pages/implementations/prometheus.adoc

@@ -43,7 +43,7 @@ catch (IOException e) {
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 <1> The `PrometheusMeterRegistry` has a `scrape()` function that knows how to supply the String data necessary for the scrape. All you have to do is wire it to an endpoint.
 
-If you use the "new" client (`micrometer-registry-prometheus`), you can alternatively use `io.prometheus.metrics.exporter.httpserver.HTTPServer`, which you can find in `io.prometheus:prometheus-metrics-exporter-httpserver`:
+If you use the "new" client (`micrometer-registry-prometheus`), you can alternatively use `io.prometheus.metrics.exporter.httpserver.HTTPServer`, which you can find in `io.prometheus:prometheus-metrics-exporter-httpserver` (you need to add it as a dependency if you want to use it):
 
 [source,java]
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