Use addSamplerCustomizer in demo extension (#6204)

* Use addSamplerCustomizer in demo extension

* Switch to ConfigurableSamplerProvider

examples/extension/src/main/java/com/example/javaagent/DemoAutoConfigurationCustomizerProvider.java

@@ -38,7 +38,6 @@ public class DemoAutoConfigurationCustomizerProvider
     return tracerProvider
         .setIdGenerator(new DemoIdGenerator())
         .setSpanLimits(SpanLimits.builder().setMaxNumberOfAttributes(1024).build())
-        .setSampler(new DemoSampler())
         .addSpanProcessor(new DemoSpanProcessor())
         .addSpanProcessor(SimpleSpanProcessor.create(new DemoSpanExporter()));
   }

examples/extension/src/main/java/com/example/javaagent/DemoConfigurableSamplerProvider.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.example.javaagent;
+
+import com.google.auto.service.AutoService;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.opentelemetry.sdk.autoconfigure.spi.traces.ConfigurableSamplerProvider;
+import io.opentelemetry.sdk.trace.samplers.Sampler;
+
+@AutoService(ConfigurableSamplerProvider.class)
+public class DemoConfigurableSamplerProvider implements ConfigurableSamplerProvider {
+
+  @Override
+  public Sampler createSampler(ConfigProperties config) {
+    return new DemoSampler();
+  }
+
+  @Override
+  public String getName() {
+    return "demo";
+  }
+}

examples/extension/src/main/java/com/example/javaagent/DemoPropertySource.java

@@ -25,6 +25,7 @@ public class DemoPropertySource implements ConfigPropertySource {
     properties.put("otel.exporter.otlp.endpoint", "http://backend:8080");
     properties.put("otel.exporter.otlp.insecure", "true");
     properties.put("otel.config.max.attrs", "16");
+    properties.put("otel.traces.sampler", "demo");
     return properties;
   }
 }