javadocs
diff --git a/src/main/java/org/cloudera/htrace/impl/TrueIfTracingSampler.java b/src/main/java/org/cloudera/htrace/impl/TrueIfTracingSampler.java
index 3689371..1c82b43 100644
--- a/src/main/java/org/cloudera/htrace/impl/TrueIfTracingSampler.java
+++ b/src/main/java/org/cloudera/htrace/impl/TrueIfTracingSampler.java
@@ -5,6 +5,9 @@
 import org.cloudera.htrace.Sampler;
 import org.cloudera.htrace.Trace;
 
+/**
+ * A Sampler that returns true if and only if tracing is on the current thread.
+ */
 @InterfaceAudience.Public
 @InterfaceStability.Evolving
 public class TrueIfTracingSampler implements Sampler<Object> {