Revert "Preserve the caller's stacktrace for blocking API (#2420)" (#…

…2488)

This reverts commit 8b41bf4.

Motivation: 

There are cases when Netty's DNS resolver may put an exception into the cache and return it multiple times. In this case, we keep adding suppressed exceptions to the same instance and it leads to a memory leak and increased logging output.
Let's revert this feature before the upcoming release and revisit later when we figure out the approach for Netty/ST DNS resolver.

servicetalk-concurrent-api-internal/src/main/java/io/servicetalk/concurrent/api/internal/BlockingUtils.java

@@ -21,7 +21,7 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 
-import static io.servicetalk.utils.internal.ThrowableUtils.throwException;
+import static io.servicetalk.utils.internal.PlatformDependent.throwException;
 
 /**
  * Common utility functions to unwrap {@link ExecutionException} from async operations.
@@ -50,7 +50,7 @@ public static <T> T futureGetCancelOnInterrupt(Future<T> future) throws Exceptio
             future.cancel(false);
             throw e;
         } catch (ExecutionException e) {
-            return throwException(unwrapExecutionException(e));
+            return throwException(executionExceptionCause(e));
         }
     }
 
@@ -69,7 +69,7 @@ public static <T> T blockingInvocation(Single<T> source) throws Exception {
         try {
             return source.toFuture().get();
         } catch (final ExecutionException e) {
-            return throwException(unwrapExecutionException(e));
+            return throwException(executionExceptionCause(e));
         }
     }
 
@@ -86,31 +86,11 @@ public static void blockingInvocation(Completable source) throws Exception {
         try {
             source.toFuture().get();
         } catch (final ExecutionException e) {
-            throwException(unwrapExecutionException(e));
+            throwException(executionExceptionCause(e));
         }
     }
 
-    private static Throwable unwrapExecutionException(ExecutionException ee) {
-        final Throwable cause = ee.getCause();
-        if (cause == null) {
-            return ee;
-        }
-        cause.addSuppressed(new SuppressedExecutionException(ee));
-        return cause;
-    }
-
-    private static final class SuppressedExecutionException extends ExecutionException {
-        private static final long serialVersionUID = 2001711259056665126L;
-
-        SuppressedExecutionException(final ExecutionException original) {
-            super("Blocking operation terminated with an error");
-            setStackTrace(original.getStackTrace());
-        }
-
-        @Override
-        public synchronized Throwable fillInStackTrace() {
-            // We inherit the stack-trace from the original ExecutionException
-            return this;
-        }
+    private static Throwable executionExceptionCause(ExecutionException original) {
+        return (original.getCause() != null) ? original.getCause() : original;
     }
 }