Fix adding a generic parameter failing

temporal-sdk/src/main/java/io/temporal/common/converter/DataConverter.java

@@ -3,6 +3,7 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.base.Defaults;
 import com.google.common.base.Preconditions;
+import com.google.common.reflect.TypeToken;
 import io.temporal.api.common.v1.Payload;
 import io.temporal.api.common.v1.Payloads;
 import io.temporal.api.failure.v1.Failure;
@@ -132,7 +133,7 @@ default Object[] fromPayloads(
     if (!content.isPresent()) {
       // Return defaults for all the parameters
       for (int i = 0; i < parameterTypes.length; i++) {
-        result[i] = Defaults.defaultValue((Class<?>) genericParameterTypes[i]);
+        result[i] = Defaults.defaultValue(TypeToken.of(genericParameterTypes[i]).getRawType());
       }
       return result;
     }
@@ -142,7 +143,7 @@ default Object[] fromPayloads(
       Class<?> pt = parameterTypes[i];
       Type gt = genericParameterTypes[i];
       if (i >= count) {
-        result[i] = Defaults.defaultValue((Class<?>) gt);
+        result[i] = Defaults.defaultValue(TypeToken.of(gt).getRawType());
       } else {
         result[i] = this.fromPayload(payloads.getPayloads(i), pt, gt);
       }

temporal-sdk/src/test/java/io/temporal/common/converter/DataConverterTest.java

@@ -0,0 +1,64 @@
+package io.temporal.common.converter;
+
+import io.temporal.api.common.v1.Payloads;
+import java.lang.reflect.Method;
+import java.util.List;
+import java.util.Optional;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class DataConverterTest {
+  // Test methods for reflection
+  public String testMethodNormalParameter(String input, String names) {
+    return "";
+  }
+
+  public String testMethodGenericParameter(String input, List<String> names) {
+    return "";
+  }
+
+  public String testMethodGenericArrayParameter(String input, List<Integer>[] names) {
+    return "";
+  }
+
+  @Test
+  public void noContent() throws NoSuchMethodException {
+    DataConverter dc = GlobalDataConverter.get();
+    Method m = this.getClass().getMethod("testMethodGenericParameter", String.class, List.class);
+    Object[] result =
+        dc.fromPayloads(Optional.empty(), m.getParameterTypes(), m.getGenericParameterTypes());
+    Assert.assertNull(result[0]);
+    Assert.assertNull(result[1]);
+  }
+
+  @Test
+  public void addParameter() throws NoSuchMethodException {
+    DataConverter dc = GlobalDataConverter.get();
+    Optional<Payloads> p = dc.toPayloads("test");
+    Method m = this.getClass().getMethod("testMethodNormalParameter", String.class, String.class);
+    Object[] result = dc.fromPayloads(p, m.getParameterTypes(), m.getGenericParameterTypes());
+    Assert.assertEquals("test", result[0]);
+    Assert.assertNull(result[1]);
+  }
+
+  @Test
+  public void addGenericParameter() throws NoSuchMethodException {
+    DataConverter dc = GlobalDataConverter.get();
+    Optional<Payloads> p = dc.toPayloads("test");
+    Method m = this.getClass().getMethod("testMethodGenericParameter", String.class, List.class);
+    Object[] result = dc.fromPayloads(p, m.getParameterTypes(), m.getGenericParameterTypes());
+    Assert.assertEquals("test", result[0]);
+    Assert.assertNull(result[1]);
+  }
+
+  @Test
+  public void addGenericArrayParameter() throws NoSuchMethodException {
+    DataConverter dc = GlobalDataConverter.get();
+    Optional<Payloads> p = dc.toPayloads("test");
+    Method m =
+        this.getClass().getMethod("testMethodGenericArrayParameter", String.class, List[].class);
+    Object[] result = dc.fromPayloads(p, m.getParameterTypes(), m.getGenericParameterTypes());
+    Assert.assertEquals("test", result[0]);
+    Assert.assertNull(result[1]);
+  }
+}

temporal-sdk/src/test/java/io/temporal/workflow/GenericParametersWorkflowTest.java

@@ -2,6 +2,8 @@
 
 import io.temporal.activity.ActivityInterface;
 import io.temporal.client.WorkflowClient;
+import io.temporal.client.WorkflowStub;
+import io.temporal.failure.ApplicationFailure;
 import io.temporal.testing.internal.SDKTestOptions;
 import io.temporal.testing.internal.SDKTestWorkflowRule;
 import java.time.Duration;
@@ -19,7 +21,8 @@ public class GenericParametersWorkflowTest {
   @Rule
   public SDKTestWorkflowRule testWorkflowRule =
       SDKTestWorkflowRule.newBuilder()
-          .setWorkflowTypes(GenericParametersWorkflowImpl.class)
+          .setWorkflowTypes(
+              GenericParametersWorkflowImpl.class, MissingGenericParametersWorkflowImpl.class)
           .setActivityImplementations(activitiesImpl)
           .build();
 
@@ -119,4 +122,31 @@ public List<UUID> query(List<UUID> arg) {
       return result;
     }
   }
+
+  @Test
+  public void testMissingGenericParameter() {
+    WorkflowStub untypedStub =
+        testWorkflowRule.newUntypedWorkflowStub("MissingGenericParametersWorkflow");
+    untypedStub.start(testWorkflowRule.getTaskQueue());
+    String result = untypedStub.getResult(String.class);
+    Assert.assertEquals(testWorkflowRule.getTaskQueue(), result);
+  }
+
+  @WorkflowInterface
+  public interface MissingGenericParametersWorkflow {
+    @WorkflowMethod
+    String execute(String name, List<String> names);
+  }
+
+  public static class MissingGenericParametersWorkflowImpl
+      implements MissingGenericParametersWorkflow {
+    @Override
+    public String execute(String name, List<String> names) {
+      if (names != null) {
+        throw ApplicationFailure.newFailure(
+            "Generic parameter should not be present", "GenericParameterError");
+      }
+      return name;
+    }
+  }
 }