Include Exception Properties at FailureDetails

client/build.gradle

@@ -57,7 +57,8 @@ compileTestJava {
     sourceCompatibility = JavaVersion.VERSION_11
     targetCompatibility = JavaVersion.VERSION_11
     options.fork = true
-    options.forkOptions.executable = "${PATH_TO_TEST_JAVA_RUNTIME}/bin/javac"
+    def javacName = org.gradle.internal.os.OperatingSystem.current().isWindows() ? 'javac.exe' : 'javac'
+    options.forkOptions.executable = "${PATH_TO_TEST_JAVA_RUNTIME}/bin/${javacName}"
 }
 
 task downloadProtoFiles {
@@ -90,7 +91,9 @@ protobuf {
     }
     generateProtoTasks {
         all()*.plugins { grpc {} }
-        all()*.dependsOn downloadProtoFiles
+        if (project.gradle.startParameter.taskNames.any { it.contains('downloadProtoFiles') }) {
+            all()*.dependsOn downloadProtoFiles
+        }
     }
 }
 
@@ -107,7 +110,8 @@ sourceSets {
 }
 
 tasks.withType(Test) {
-    executable = new File("${PATH_TO_TEST_JAVA_RUNTIME}", 'bin/java')
+    def javaName = org.gradle.internal.os.OperatingSystem.current().isWindows() ? 'java.exe' : 'java'
+    executable = new File("${PATH_TO_TEST_JAVA_RUNTIME}", "bin/${javaName}")
 }
 
 test {

client/src/main/java/com/microsoft/durabletask/DurableTaskGrpcWorker.java

@@ -34,6 +34,7 @@ public final class DurableTaskGrpcWorker implements AutoCloseable {
     private final DataConverter dataConverter;
     private final Duration maximumTimerInterval;
     private final DurableTaskGrpcWorkerVersioningOptions versioningOptions;
+    private final ExceptionPropertiesProvider exceptionPropertiesProvider;
 
     private final TaskHubSidecarServiceBlockingStub sidecarClient;
 
@@ -65,6 +66,7 @@ public final class DurableTaskGrpcWorker implements AutoCloseable {
         this.dataConverter = builder.dataConverter != null ? builder.dataConverter : new JacksonDataConverter();
         this.maximumTimerInterval = builder.maximumTimerInterval != null ? builder.maximumTimerInterval : DEFAULT_MAXIMUM_TIMER_INTERVAL;
         this.versioningOptions = builder.versioningOptions;
+        this.exceptionPropertiesProvider = builder.exceptionPropertiesProvider;
     }
 
     /**
@@ -118,7 +120,8 @@ public void startAndBlock() {
                 this.dataConverter,
                 this.maximumTimerInterval,
                 logger,
-                this.versioningOptions);
+                this.versioningOptions,
+                this.exceptionPropertiesProvider);
         TaskActivityExecutor taskActivityExecutor = new TaskActivityExecutor(
                 this.activityFactories,
                 this.dataConverter,
@@ -228,11 +231,9 @@ public void startAndBlock() {
                                 activityRequest.getInput().getValue(),
                                 activityRequest.getTaskId());
                         } catch (Throwable e) {
-                            failureDetails = TaskFailureDetails.newBuilder()
-                                .setErrorType(e.getClass().getName())
-                                .setErrorMessage(e.getMessage())
-                                .setStackTrace(StringValue.of(FailureDetails.getFullStackTrace(e)))
-                                .build();
+                            Exception ex = e instanceof Exception ? (Exception) e : new RuntimeException(e);
+                            failureDetails = FailureDetails.fromException(
+                                    ex, this.exceptionPropertiesProvider).toProto();
                         }
 
                         ActivityResponse.Builder responseBuilder = ActivityResponse.newBuilder()

client/src/main/java/com/microsoft/durabletask/DurableTaskGrpcWorkerBuilder.java

@@ -18,6 +18,7 @@ public final class DurableTaskGrpcWorkerBuilder {
     DataConverter dataConverter;
     Duration maximumTimerInterval;
     DurableTaskGrpcWorkerVersioningOptions versioningOptions;
+    ExceptionPropertiesProvider exceptionPropertiesProvider;
 
     /**
      * Adds an orchestration factory to be used by the constructed {@link DurableTaskGrpcWorker}.
@@ -125,6 +126,21 @@ public DurableTaskGrpcWorkerBuilder useVersioning(DurableTaskGrpcWorkerVersionin
         return this;
     }
 
+    /**
+     * Sets the {@link ExceptionPropertiesProvider} to use for extracting custom properties from exceptions.
+     * <p>
+     * When set, the provider is invoked whenever an activity or orchestration fails with an exception. The returned
+     * properties are included in the {@link FailureDetails} and can be retrieved via
+     * {@link FailureDetails#getProperties()}.
+     *
+     * @param provider the exception properties provider
+     * @return this builder object
+     */
+    public DurableTaskGrpcWorkerBuilder exceptionPropertiesProvider(ExceptionPropertiesProvider provider) {
+        this.exceptionPropertiesProvider = provider;
+        return this;
+    }
+
     /**
      * Initializes a new {@link DurableTaskGrpcWorker} object with the settings specified in the current builder object.
      * @return a new {@link DurableTaskGrpcWorker} object

client/src/main/java/com/microsoft/durabletask/ExceptionPropertiesProvider.java

@@ -0,0 +1,45 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+package com.microsoft.durabletask;
+
+import javax.annotation.Nullable;
+import java.util.Map;
+
+/**
+ * Provider interface for extracting custom properties from exceptions.
+ * <p>
+ * Implementations of this interface can be registered with a {@link DurableTaskGrpcWorkerBuilder} to include
+ * custom exception properties in {@link FailureDetails} when activities or orchestrations fail.
+ * These properties are then available via {@link FailureDetails#getProperties()}.
+ * <p>
+ * Example usage:
+ * <pre>{@code
+ * DurableTaskGrpcWorker worker = new DurableTaskGrpcWorkerBuilder()
+ *     .exceptionPropertiesProvider(exception -> {
+ *         if (exception instanceof MyCustomException) {
+ *             MyCustomException custom = (MyCustomException) exception;
+ *             Map<String, Object> props = new HashMap<>();
+ *             props.put("errorCode", custom.getErrorCode());
+ *             props.put("retryable", custom.isRetryable());
+ *             return props;
+ *         }
+ *         return null;
+ *     })
+ *     .addOrchestration(...)
+ *     .build();
+ * }</pre>
+ */
+@FunctionalInterface
+public interface ExceptionPropertiesProvider {
+
+    /**
+     * Extracts custom properties from the given exception.
+     * <p>
+     * Return {@code null} or an empty map if no custom properties should be included for this exception.
+     *
+     * @param exception the exception to extract properties from
+     * @return a map of property names to values, or {@code null}
+     */
+    @Nullable
+    Map<String, Object> getExceptionProperties(Exception exception);
+}

client/src/main/java/com/microsoft/durabletask/FailureDetails.java

@@ -2,11 +2,16 @@
 // Licensed under the MIT License.
 package com.microsoft.durabletask;
 
+import com.google.protobuf.NullValue;
 import com.google.protobuf.StringValue;
+import com.google.protobuf.Value;
 import com.microsoft.durabletask.implementation.protobuf.OrchestratorService.TaskFailureDetails;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
 
 /**
  * Class that represents the details of a task failure.
@@ -20,29 +25,76 @@ public final class FailureDetails {
     private final String errorMessage;
     private final String stackTrace;
     private final boolean isNonRetriable;
+    private final FailureDetails innerFailure;
+    private final Map<String, Object> properties;
 
     FailureDetails(
             String errorType,
             @Nullable String errorMessage,
             @Nullable String errorDetails,
             boolean isNonRetriable) {
+        this(errorType, errorMessage, errorDetails, isNonRetriable, null, null);
+    }
+
+    FailureDetails(
+            String errorType,
+            @Nullable String errorMessage,
+            @Nullable String errorDetails,
+            boolean isNonRetriable,
+            @Nullable FailureDetails innerFailure,
+            @Nullable Map<String, Object> properties) {
         this.errorType = errorType;
         this.stackTrace = errorDetails;
 
         // Error message can be null for things like NullPointerException but the gRPC contract doesn't allow null
         this.errorMessage = errorMessage != null ? errorMessage : "";
         this.isNonRetriable = isNonRetriable;
+        this.innerFailure = innerFailure;
+        this.properties = properties != null ? Collections.unmodifiableMap(new HashMap<>(properties)) : null;
     }
 
     FailureDetails(Exception exception) {
-        this(exception.getClass().getName(), exception.getMessage(), getFullStackTrace(exception), false);
+        this(exception.getClass().getName(),
+             exception.getMessage(),
+             getFullStackTrace(exception),
+             false,
+             exception.getCause() != null ? fromExceptionRecursive(exception.getCause(), null) : null,
+             null);
+    }
+
+    /**
+     * Creates a {@code FailureDetails} from an exception, optionally using the provided
+     * {@link ExceptionPropertiesProvider} to extract custom properties.
+     *
+     * @param exception the exception that caused the failure
+     * @param provider  the provider for extracting custom properties, or {@code null}
+     * @return a new {@code FailureDetails} instance
+     */
+    static FailureDetails fromException(Exception exception, @Nullable ExceptionPropertiesProvider provider) {
+        Map<String, Object> properties = null;
+        if (provider != null) {
+            try {
+                properties = provider.getExceptionProperties(exception);
+            } catch (Exception ignored) {
+                // Don't let provider errors mask the original failure
+            }
+        }
+        return new FailureDetails(
+                exception.getClass().getName(),
+                exception.getMessage(),
+                getFullStackTrace(exception),
+                false,
+                exception.getCause() != null ? fromExceptionRecursive(exception.getCause(), provider) : null,
+                properties);
     }
 
     FailureDetails(TaskFailureDetails proto) {
         this(proto.getErrorType(),
              proto.getErrorMessage(),
              proto.getStackTrace().getValue(),
-             proto.getIsNonRetriable());
+             proto.getIsNonRetriable(),
+             proto.hasInnerFailure() ? new FailureDetails(proto.getInnerFailure()) : null,
+             convertProtoProperties(proto.getPropertiesMap()));
     }
 
     /**
@@ -86,6 +138,28 @@ public boolean isNonRetriable() {
         return this.isNonRetriable;
     }
 
+    /**
+     * Gets the inner failure that caused this failure, or {@code null} if there is no inner cause.
+     *
+     * @return the inner {@code FailureDetails} or {@code null}
+     */
+    @Nullable
+    public FailureDetails getInnerFailure() {
+        return this.innerFailure;
+    }
+
+    /**
+     * Gets additional properties associated with the exception, or {@code null} if no properties are available.
+     * <p>
+     * The returned map is unmodifiable.
+     *
+     * @return an unmodifiable map of property names to values, or {@code null}
+     */
+    @Nullable
+    public Map<String, Object> getProperties() {
+        return this.properties;
+    }
+
     /**
      * Returns {@code true} if the task failure was provided by the specified exception type, otherwise {@code false}.
      * <p>
@@ -112,6 +186,11 @@ public boolean isCausedBy(Class<? extends Exception> exceptionClass) {
         }
     }
 
+    @Override
+    public String toString() {
+        return this.errorType + ": " + this.errorMessage;
+    }
+
     static String getFullStackTrace(Throwable e) {
         StackTraceElement[] elements = e.getStackTrace();
 
@@ -124,10 +203,98 @@ static String getFullStackTrace(Throwable e) {
     }
 
     TaskFailureDetails toProto() {
-        return TaskFailureDetails.newBuilder()
+        TaskFailureDetails.Builder builder = TaskFailureDetails.newBuilder()
                 .setErrorType(this.getErrorType())
                 .setErrorMessage(this.getErrorMessage())
                 .setStackTrace(StringValue.of(this.getStackTrace() != null ? this.getStackTrace() : ""))
-                .build();
+                .setIsNonRetriable(this.isNonRetriable);
+
+        if (this.innerFailure != null) {
+            builder.setInnerFailure(this.innerFailure.toProto());
+        }
+
+        if (this.properties != null) {
+            builder.putAllProperties(convertToProtoProperties(this.properties));
+        }
+
+        return builder.build();
+    }
+
+    @Nullable
+    private static FailureDetails fromExceptionRecursive(
+            @Nullable Throwable exception,
+            @Nullable ExceptionPropertiesProvider provider) {
+        if (exception == null) {
+            return null;
+        }
+        Map<String, Object> properties = null;
+        if (provider != null && exception instanceof Exception) {
+            try {
+                properties = provider.getExceptionProperties((Exception) exception);
+            } catch (Exception ignored) {
+                // Don't let provider errors mask the original failure
+            }
+        }
+        return new FailureDetails(
+                exception.getClass().getName(),
+                exception.getMessage(),
+                getFullStackTrace(exception),
+                false,
+                exception.getCause() != null ? fromExceptionRecursive(exception.getCause(), provider) : null,
+                properties);
+    }
+
+    @Nullable
+    private static Map<String, Object> convertProtoProperties(Map<String, Value> protoProperties) {
+        if (protoProperties == null || protoProperties.isEmpty()) {
+            return null;
+        }
+
+        Map<String, Object> result = new HashMap<>();
+        for (Map.Entry<String, Value> entry : protoProperties.entrySet()) {
+            result.put(entry.getKey(), convertProtoValue(entry.getValue()));
+        }
+        return result;
+    }
+
+    @Nullable
+    private static Object convertProtoValue(Value value) {
+        if (value == null) {
+            return null;
+        }
+        switch (value.getKindCase()) {
+            case NULL_VALUE:
+                return null;
+            case NUMBER_VALUE:
+                return value.getNumberValue();
+            case STRING_VALUE:
+                return value.getStringValue();
+            case BOOL_VALUE:
+                return value.getBoolValue();
+            default:
+                return value.toString();
+        }
+    }
+
+    private static Map<String, Value> convertToProtoProperties(Map<String, Object> properties) {
+        Map<String, Value> result = new HashMap<>();
+        for (Map.Entry<String, Object> entry : properties.entrySet()) {
+            result.put(entry.getKey(), convertToProtoValue(entry.getValue()));
+        }
+        return result;
+    }
+
+    private static Value convertToProtoValue(@Nullable Object obj) {
+        if (obj == null) {
+            return Value.newBuilder().setNullValue(NullValue.NULL_VALUE).build();
+        } else if (obj instanceof Number) {
+            return Value.newBuilder().setNumberValue(((Number) obj).doubleValue()).build();
+        } else if (obj instanceof Boolean) {
+            return Value.newBuilder().setBoolValue((Boolean) obj).build();
+        } else if (obj instanceof String) {
+            return Value.newBuilder().setStringValue((String) obj).build();
+        } else {
+            return Value.newBuilder().setStringValue(obj.toString()).build();
+        }
     }
-}
+}