stabilize LocalRootSpan (#1683)

Author: brettmc

Trace/LocalRootSpan.php

@@ -8,16 +8,12 @@
 use OpenTelemetry\Context\ContextInterface;
 use OpenTelemetry\Context\ContextKeyInterface;
 
-/**
- * @experimental
- */
 class LocalRootSpan
 {
     /**
      * Retrieve the local root span. This is the root-most active span which has
      * a remote or invalid parent.
      * If there is no active local root span, then an invalid span is returned.
-     * @experimental
      */
     public static function current(): SpanInterface
     {
@@ -26,7 +22,6 @@ public static function current(): SpanInterface
 
     /**
      * Retrieve the local root span from a Context.
-     * @experimental
      */
     public static function fromContext(ContextInterface $context): SpanInterface
     {
@@ -43,6 +38,7 @@ public static function store(ContextInterface $context, SpanInterface $span): Co
 
     /**
      * @internal
+     * @return ContextKeyInterface<SpanInterface>
      */
     public static function key(): ContextKeyInterface
     {