Update Exporter.Shutdown to meet with the latest spec (#1285)

* exporter.Shutdown returns bool

* update changelog

Co-authored-by: Cijo Thomas <cithomas@microsoft.com>
Co-authored-by: Mikel Blanchard <mblanchard@macrosssoftware.com>

Author: 3 people

docs/trace/extending-the-sdk/MyExporter.cs

@@ -50,9 +50,10 @@ public override ExportResult Export(in Batch<Activity> batch)
         return ExportResult.Success;
     }
 
-    protected override void OnShutdown(int timeoutMilliseconds)
+    protected override bool OnShutdown(int timeoutMilliseconds)
     {
         Console.WriteLine($"{this.name}.OnShutdown(timeoutMilliseconds={timeoutMilliseconds})");
+        return true;
     }
 
     protected override void Dispose(bool disposing)

src/OpenTelemetry/CHANGELOG.md

@@ -2,9 +2,11 @@
 
 ## Unreleased
 
-* Changed `ActivityProcessor.OnShutdown` and `ActivityProcessor.Shutdown` to
-  return boolean value
+* Changed `ActivityExporter.OnShutdown`, `ActivityExporter.Shutdown`,
+  `ActivityProcessor.OnShutdown` and `ActivityProcessor.Shutdown` to return
+  boolean value
   ([#1282](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1282))
+  ([#1285](https://github.com/open-telemetry/opentelemetry-dotnet/pull/1285))
 
 ## 0.6.0-beta.1
 

src/OpenTelemetry/Trace/ActivityExporter.cs

@@ -83,8 +83,7 @@ public bool Shutdown(int timeoutMilliseconds = Timeout.Infinite)
 
             try
             {
-                this.OnShutdown(timeoutMilliseconds);
-                return true; // TODO: update exporter.OnShutdown to return boolean
+                return this.OnShutdown(timeoutMilliseconds);
             }
             catch (Exception ex)
             {
@@ -108,13 +107,17 @@ public void Dispose()
         /// The number of milliseconds to wait, or <c>Timeout.Infinite</c> to
         /// wait indefinitely.
         /// </param>
+        /// <returns>
+        /// Returns <c>true</c> when shutdown succeeded; otherwise, <c>false</c>.
+        /// </returns>
         /// <remarks>
         /// This function is called synchronously on the thread which made the
         /// first call to <c>Shutdown</c>. This function should not throw
         /// exceptions.
         /// </remarks>
-        protected virtual void OnShutdown(int timeoutMilliseconds)
+        protected virtual bool OnShutdown(int timeoutMilliseconds)
         {
+            return true;
         }
 
         /// <summary>