move SuspendExecutionException to under Error

Author: zhongkechen

sdk-integration-tests/src/test/java/software/amazon/lambda/durable/CallbackIntegrationTest.java

@@ -271,10 +271,9 @@ void waitForCallbackCallbackFailed() {
                 ctx.waitForCallback("approval", String.class, (callbackId, stepCtx) -> {});
                 fail();
                 return "should not reach here";
+            } catch (SuspendExecutionException e) {
+                throw e;
             } catch (Exception e) {
-                if (e instanceof SuspendExecutionException) {
-                    throw e;
-                }
                 assertInstanceOf(CallbackFailedException.class, e);
                 throw e;
             }
@@ -309,10 +308,9 @@ void waitForCallbackCallbackTimeout() {
                 ctx.waitForCallback("approval", String.class, (callbackId, stepCtx) -> {});
                 fail();
                 return "should not reach here";
+            } catch (SuspendExecutionException e) {
+                throw e;
             } catch (Exception e) {
-                if (e instanceof SuspendExecutionException) {
-                    throw e;
-                }
                 assertInstanceOf(CallbackTimeoutException.class, e);
                 throw e;
             }
@@ -339,10 +337,9 @@ void waitForCallbackCallbackFailedWithUserException() {
                     // original exception
                     throw new IllegalArgumentException(errorMessage);
                 });
+            } catch (SuspendExecutionException e) {
+                throw e;
             } catch (Exception e) {
-                if (e instanceof SuspendExecutionException) {
-                    throw e;
-                }
                 assertInstanceOf(IllegalArgumentException.class, e);
                 assertEquals(errorMessage, e.getMessage());
                 throw e;

sdk/src/main/java/software/amazon/lambda/durable/execution/DurableExecutionError.java

@@ -0,0 +1,13 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+package software.amazon.lambda.durable.execution;
+
+/**
+ * A throwable error that can be used internally by Durable Execution SDK. Users of the SDK should not throw this error
+ * directly or catch this error in their code.
+ */
+public class DurableExecutionError extends Error {
+    public DurableExecutionError(String message) {
+        super(message);
+    }
+}

sdk/src/main/java/software/amazon/lambda/durable/execution/SuspendExecutionException.java

@@ -3,7 +3,7 @@
 package software.amazon.lambda.durable.execution;
 
 /** Exception thrown to suspend execution during wait operations. This is an internal control flow mechanism. */
-public class SuspendExecutionException extends RuntimeException {
+public class SuspendExecutionException extends DurableExecutionError {
     public SuspendExecutionException() {
         super("Execution suspended for wait operation");
     }