Remove getDescription

Author: anuraaga

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/trace/samplers/ComposableRuleBasedSampler.java

@@ -25,7 +25,7 @@ final class ComposableRuleBasedSampler implements ComposableSampler {
     if (this.rules.length > 0) {
       for (SamplingRule rule : this.rules) {
         description.append('(');
-        description.append(rule.predicate().getDescription());
+        description.append(rule.predicate().toString());
         description.append(':');
         description.append(rule.sampler().getDescription());
         description.append(')');

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/trace/samplers/SamplingPredicate.java

@@ -11,7 +11,14 @@
 import io.opentelemetry.sdk.trace.data.LinkData;
 import java.util.List;
 
-/** A predicate for a composable sampler, indicating whether a set of sampling arguments matches. */
+/**
+ * A predicate for a composable sampler, indicating whether a set of sampling arguments matches.
+ *
+ * <p>While this can be implemented with lambda expressions, it is recommended to implement {@link
+ * Object#toString()} as well with an explanation of the predicate for rendering in {@link
+ * io.opentelemetry.sdk.trace.samplers.Sampler#getDescription()}.
+ */
+@FunctionalInterface
 public interface SamplingPredicate {
   /** Returns whether this {@link SamplingPredicate} matches the given sampling arguments. */
   boolean matches(
@@ -21,10 +28,4 @@ boolean matches(
       SpanKind spanKind,
       Attributes attributes,
       List<LinkData> parentLinks);
-
-  /**
-   * Returns a description of the {@link SamplingPredicate}. This may be displayed on debug pages or
-   * in the logs.
-   */
-  String getDescription();
 }

sdk-extensions/incubator/src/test/java/io/opentelemetry/sdk/extension/incubator/trace/samplers/ComposableRuleBasedSamplerTest.java

@@ -49,14 +49,9 @@ public boolean matches(
       return "/health".equals(attributes.get(key));
     }
 
-    @Override
-    public String getDescription() {
-      return description;
-    }
-
     @Override
     public String toString() {
-      return getDescription();
+      return description;
     }
   }
 
@@ -75,7 +70,7 @@ public boolean matches(
     }
 
     @Override
-    public String getDescription() {
+    public String toString() {
       return "isRoot";
     }
   }