add experimental- suffix, add test

Author: zeitlinger

span-stacktrace/src/main/java/io/opentelemetry/contrib/stacktrace/StackTraceComponentProvider.java

@@ -16,7 +16,7 @@
 public class StackTraceComponentProvider implements ComponentProvider<SpanProcessor> {
   @Override
   public String getName() {
-    return "stacktrace";
+    return "experimental-stacktrace";
   }
 
   @Override

span-stacktrace/src/test/java/io/opentelemetry/contrib/stacktrace/StackTraceComponentProviderTest.java

@@ -0,0 +1,27 @@
+package io.opentelemetry.contrib.stacktrace;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.extension.incubator.fileconfig.DeclarativeConfiguration;
+import java.io.ByteArrayInputStream;
+import java.nio.charset.StandardCharsets;
+import org.junit.jupiter.api.Test;
+
+class StackTraceComponentProviderTest {
+  @Test
+   void endToEnd() {
+     String yaml =
+         "file_format: 0.4\n"
+             + "tracer_provider:\n"
+             + "  processors:\n"
+             + "    - experimental-stacktrace:\n";
+
+     OpenTelemetrySdk openTelemetrySdk =
+         DeclarativeConfiguration.parseAndCreate(
+             new ByteArrayInputStream(yaml.getBytes(StandardCharsets.UTF_8)));
+
+    assertThat(openTelemetrySdk.getSdkTracerProvider().toString())
+        .contains("StackTraceSpanProcessor");
+   }
+}