update javadoc for Attribute and AttributeReturnValue

Author: Duncan-tree-zhou

instrumentation-annotations-incubator/src/main/java/io/opentelemetry/instrumentation/annotations/incubator/Attribute.java

@@ -14,6 +14,9 @@
  * This annotation marks that a parameter of a method or constructor annotated with {@link Timed} or
  * {@link Counted} should be added as an attribute to the metric.
  *
+ * <p>By default, the `{@link Object#toString()}` will be called on the parameter value to convert
+ * it to a String.
+ *
  * <p>Application developers can use this annotation to signal OpenTelemetry auto-instrumentation
  * that the attribute should be captured.
  *
@@ -33,8 +36,7 @@
    *
    * <p>If not specified and the code is compiled using the `{@code -parameters}` argument to
    * `javac`, the parameter name will be used instead. If the parameter name is not available, e.g.,
-   * because the code was not compiled with that flag, the attribute will be ignored. `{@link
-   * Object#toString()}` may be called on the attribute value to convert it to a String.
+   * because the code was not compiled with that flag, the attribute will be ignored.
    */
   String value() default "";
 }

instrumentation-annotations-incubator/src/main/java/io/opentelemetry/instrumentation/annotations/incubator/AttributeReturnValue.java

@@ -14,6 +14,9 @@
  * This annotation allows for adding the method return value as an attribute to metrics recorded
  * using the {@link Timed} and {@link Counted} annotations.
  *
+ * <p>By default, the {@link Object#toString()} will be called on the return value to convert it to
+ * a String.
+ *
  * <p>Application developers can use this annotation to signal OpenTelemetry auto-instrumentation
  * that the attribute should be captured.
  *
@@ -31,8 +34,7 @@
   /**
    * Attribute name for the return value.
    *
-   * <p>The name of the attribute for the return value of the method call. {@link Object#toString()}
-   * may be called on the return value to convert it to a String.
+   * <p>The name of the attribute for the return value of the method call.
    */
   String value();
 }