Skip tag extractors and contributors on immutable spans

NoopSpan (via ImmutableSpan) discards every tag, but inherited the
setTagsFrom defaults, so an extractor or contributor still ran its
metadata access and side effects with tracing disabled.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: dougqh

internal-api/src/main/java/datadog/trace/bootstrap/instrumentation/api/ImmutableSpan.java

@@ -62,6 +62,20 @@ public AgentSpan setAllTags(Map<String, ?> map) {
     return this;
   }
 
+  /** Skips the extractor: its tags would be discarded, so its work and side effects are wasted. */
+  @Override
+  public <T> AgentSpan setTagsFrom(T source, TagExtractor<T> extractor) {
+    return this;
+  }
+
+  /**
+   * Skips the contributor: its tags would be discarded, so its work and side effects are wasted.
+   */
+  @Override
+  public AgentSpan setTagsFrom(TagContributor contributor) {
+    return this;
+  }
+
   @Override
   public AgentSpan setTag(String key, Number value) {
     return this;

internal-api/src/test/java/datadog/trace/bootstrap/instrumentation/api/AgentSpanSetTagsFromTest.java

@@ -53,4 +53,22 @@ void appliesTheContributorToThisSpan() {
   void skipsANullContributor() {
     assertSame(span, span.setTagsFrom((TagContributor) null));
   }
+
+  @Test
+  void skipsTheExtractorOnANoopSpan() {
+    TagExtractor<String> extractor = (source, target) -> calls.add(source);
+
+    assertSame(NoopSpan.INSTANCE, NoopSpan.INSTANCE.setTagsFrom("source", extractor));
+
+    assertTrue(calls.isEmpty());
+  }
+
+  @Test
+  void skipsTheContributorOnANoopSpan() {
+    TagContributor contributor = calls::add;
+
+    assertSame(NoopSpan.INSTANCE, NoopSpan.INSTANCE.setTagsFrom(contributor));
+
+    assertTrue(calls.isEmpty());
+  }
 }