Fix workflow implementation in springboot failing if no default constructor is present (#2300)

Author: Quinn-With-Two-Ns

temporal-sdk/src/main/java/io/temporal/common/metadata/POJOWorkflowImplMetadata.java

@@ -77,10 +77,18 @@ public int hashCode() {
 
   /**
    * Create POJOWorkflowImplMetadata for a workflow implementation class. The object must implement
-   * at least one workflow method.
+   * at least one workflow method. Validates the implementation can be registered.
    */
   public static POJOWorkflowImplMetadata newInstance(Class<?> implClass) {
-    return new POJOWorkflowImplMetadata(implClass, false);
+    return new POJOWorkflowImplMetadata(implClass, false, true);
+  }
+
+  /**
+   * Create POJOWorkflowImplMetadata for a workflow implementation class. The object must implement
+   * at least one workflow method. Does not validate the implementation can be registered.
+   */
+  public static POJOWorkflowImplMetadata newInstanceForWorkflowFactory(Class<?> implClass) {
+    return new POJOWorkflowImplMetadata(implClass, false, false);
   }
 
   /**
@@ -89,10 +97,11 @@ public static POJOWorkflowImplMetadata newInstance(Class<?> implClass) {
    * signal methods.
    */
   public static POJOWorkflowImplMetadata newListenerInstance(Class<?> implClass) {
-    return new POJOWorkflowImplMetadata(implClass, true);
+    return new POJOWorkflowImplMetadata(implClass, true, false);
   }
 
-  private POJOWorkflowImplMetadata(Class<?> implClass, boolean listener) {
+  private POJOWorkflowImplMetadata(
+      Class<?> implClass, boolean listener, boolean validateConstructor) {
     if (implClass.isInterface()
         || implClass.isPrimitive()
         || implClass.isAnnotation()
@@ -166,7 +175,7 @@ private POJOWorkflowImplMetadata(Class<?> implClass, boolean listener) {
     this.queryMethods = ImmutableList.copyOf(queryMethods.values());
     this.updateMethods = ImmutableList.copyOf(updateMethods.values());
     this.updateValidatorMethods = ImmutableList.copyOf(updateValidatorMethods.values());
-    if (!listener) {
+    if (!listener && validateConstructor) {
       this.workflowInit =
           ReflectionUtils.getConstructor(
                   implClass,

temporal-sdk/src/test/java/io/temporal/common/metadata/POJOWorkflowImplMetadataTest.java

@@ -229,6 +229,23 @@ public void testWorkflowWithConstructor() {
     Assert.assertNull(meta.getWorkflowInit());
   }
 
+  @Test
+  public void testWorkflowWithConstructorArgsNoInit() {
+    try {
+      POJOWorkflowImplMetadata.newInstance(WorkflowWithConstructorParameters.class);
+      Assert.fail();
+    } catch (IllegalArgumentException e) {
+      assertTrue(
+          e.getMessage()
+              .contains(
+                  "No default constructor or constructor annotated with @WorkflowInit found:"));
+    }
+    POJOWorkflowImplMetadata meta =
+        POJOWorkflowImplMetadata.newInstanceForWorkflowFactory(
+            WorkflowWithConstructorParameters.class);
+    Assert.assertEquals(1, meta.getWorkflowMethods().size());
+  }
+
   public static class GImpl implements POJOWorkflowInterfaceMetadataTest.G {
     @Override
     public void g() {}
@@ -377,4 +394,13 @@ public WorkflowWithConstructor() {}
     @Override
     public void i() {}
   }
+
+  public static class WorkflowWithConstructorParameters
+      implements POJOWorkflowInterfaceMetadataTest.I {
+
+    public WorkflowWithConstructorParameters(Integer i) {}
+
+    @Override
+    public void i() {}
+  }
 }

temporal-spring-boot-autoconfigure/src/main/java/io/temporal/spring/boot/autoconfigure/template/WorkersTemplate.java

@@ -504,7 +504,8 @@ private void configureWorkflowImplementationAutoDiscovery(
   @SuppressWarnings("unchecked")
   private <T> void configureWorkflowImplementation(Worker worker, Class<?> clazz) {
 
-    POJOWorkflowImplMetadata workflowMetadata = POJOWorkflowImplMetadata.newInstance(clazz);
+    POJOWorkflowImplMetadata workflowMetadata =
+        POJOWorkflowImplMetadata.newInstanceForWorkflowFactory(clazz);
     List<POJOWorkflowMethodMetadata> workflowMethods = workflowMetadata.getWorkflowMethods();
     if (workflowMethods.isEmpty()) {
       throw new BeanDefinitionValidationException(

temporal-spring-boot-autoconfigure/src/test/java/io/temporal/spring/boot/autoconfigure/byworkername/TestWorkflowImpl.java

@@ -26,9 +26,15 @@
 import io.temporal.workflow.NexusServiceOptions;
 import io.temporal.workflow.Workflow;
 import java.time.Duration;
+import org.springframework.context.ConfigurableApplicationContext;
 
 @WorkflowImpl(workers = "mainWorker")
 public class TestWorkflowImpl implements TestWorkflow {
+
+  // Test auto-wiring of the application context works, this is not indicative of a real-world use
+  // case as the workflow implementation should be stateless.
+  public TestWorkflowImpl(ConfigurableApplicationContext applicationContext) {}
+
   @Override
   public String execute(String input) {
     if (input.equals("nexus")) {