Adjust API to be only supplier

Author: jack-berg

api/all/src/main/java/io/opentelemetry/api/GlobalOpenTelemetry.java

@@ -121,15 +121,13 @@ public static void set(OpenTelemetry openTelemetry) {
   /**
    * Sets the {@link OpenTelemetry} that should be the global instance.
    *
-   * <p>This method calls the given {@code supplier}, converts the output to an {@link
-   * OpenTelemetry} object, and finally calls {@link #set(OpenTelemetry)}, all while holding the
+   * <p>This method calls the given {@code supplier} and calls {@link #set(OpenTelemetry)}, all while holding the
    * {@link GlobalOpenTelemetry} mutex.
    */
-  public static <T> T set(Supplier<T> supplier, Function<T, OpenTelemetry> converter) {
+  public static void set(Supplier<OpenTelemetry> supplier) {
     synchronized (mutex) {
-      T output = supplier.get();
-      set(converter.apply(output));
-      return output;
+      OpenTelemetry openTelemetry = supplier.get();
+      set(openTelemetry);
     }
   }
 

sdk-extensions/autoconfigure/src/main/java/io/opentelemetry/sdk/autoconfigure/AutoConfiguredOpenTelemetrySdkBuilder.java

@@ -41,6 +41,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -427,11 +428,12 @@ public AutoConfiguredOpenTelemetrySdk build() {
     if (!setResultAsGlobal) {
       return buildImpl();
     }
-    AutoConfiguredOpenTelemetrySdk sdk =
-        GlobalOpenTelemetry.set(
-            this::buildImpl, AutoConfiguredOpenTelemetrySdk::getOpenTelemetrySdk);
-    logger.log(Level.FINE, "Global OpenTelemetry set to {0} by autoconfiguration", sdk);
-    return sdk;
+    AtomicReference<AutoConfiguredOpenTelemetrySdk> autoConfiguredRef = new AtomicReference<>();
+    GlobalOpenTelemetry.set(() -> {
+      autoConfiguredRef.set(buildImpl());
+      return autoConfiguredRef.get().getOpenTelemetrySdk();
+    });
+    return autoConfiguredRef.get();
   }
 
   private AutoConfiguredOpenTelemetrySdk buildImpl() {