Add test and improve deserializer

- Make deserializer lenient to allowed values

Author: rpanackal

orchestration/src/main/java/com/sap/ai/sdk/orchestration/LLMModuleResultDeserializer.java

@@ -7,6 +7,7 @@
 import com.sap.ai.sdk.orchestration.client.model.LLMModuleResultStreaming;
 import com.sap.ai.sdk.orchestration.client.model.LLMModuleResultSynchronous;
 import java.io.IOException;
+import javax.annotation.Nonnull;
 
 /**
  * A deserializer for {@link LLMModuleResult} that determines the concrete implementation based on
@@ -21,58 +22,61 @@ public LLMModuleResultDeserializer() {
   /**
    * Deserialize the JSON object into one of the subtypes of the base type.
    *
+   * <ul>
+   *   <li>If elements of "choices" array contains "delta", deserialize into {@link
+   *       LLMModuleResultStreaming}.
+   *   <li>Otherwise, deserialize into {@link LLMModuleResultSynchronous}.
+   * </ul>
+   *
    * @param parser The JSON parser.
    * @param context The deserialization context.
    * @return The deserialized object.
    * @throws IOException If an I/O error occurs.
    */
   @Override
-  public LLMModuleResult deserialize(JsonParser parser, DeserializationContext context)
+  public LLMModuleResult deserialize(JsonParser parser, @Nonnull DeserializationContext context)
       throws IOException {
 
     // Check if the target type is a concrete class
     JavaType targetType = context.getContextualType();
-
     if (targetType != null && !LLMModuleResult.class.equals(targetType.getRawClass())) {
-      // If we're deserializing a concrete class, delegate to the default deserializer
-      JsonDeserializer<Object> defaultDeserializer = context.findRootValueDeserializer(targetType);
-      return (LLMModuleResult) defaultDeserializer.deserialize(parser, context);
+      return delegateToDefaultDeserializer(parser, context, targetType);
     }
 
     // Custom deserialization logic for LLMModuleResult interface
-    ObjectMapper mapper = (ObjectMapper) parser.getCodec();
-    JsonNode rootNode = mapper.readTree(parser);
+    var mapper = (ObjectMapper) parser.getCodec();
+    var rootNode = mapper.readTree(parser);
+    Class<? extends LLMModuleResult> concreteClass = LLMModuleResultSynchronous.class;
 
     // Inspect the "choices" field
-    JsonNode choicesNode = rootNode.get("choices");
-
+    var choicesNode = rootNode.get("choices");
     if (choicesNode != null && choicesNode.isArray()) {
-      JsonNode firstChoice = choicesNode.get(0);
-      if (firstChoice != null) {
-        Class<? extends LLMModuleResult> concreteClass = null;
-        if (firstChoice.has("delta")) {
-          concreteClass = LLMModuleResultStreaming.class;
-        } else if (firstChoice.has("message")) {
-          concreteClass = LLMModuleResultSynchronous.class;
-        }
-
-        if (concreteClass != null) {
-          // Deserialize into the determined concrete class
-          // Create a new parser for the root node
-          JsonParser rootParser = rootNode.traverse(mapper);
-          rootParser.nextToken(); // Advance to the first token
-
-          // Use the default deserializer for the concrete class
-          JsonDeserializer<?> deserializer =
-              context.findRootValueDeserializer(context.constructType(concreteClass));
-
-          return (LLMModuleResult) deserializer.deserialize(rootParser, context);
-        }
+      var firstChoice = (JsonNode) choicesNode.get(0);
+      if (firstChoice != null && firstChoice.has("delta")) {
+        concreteClass = LLMModuleResultStreaming.class;
       }
     }
 
-    // If unable to determine, throw an exception or handle default case
-    throw new JsonMappingException(
-        parser, "Unable to determine the concrete implementation of LLMModuleResult");
+    // Create a new parser for the root node
+    var rootParser = rootNode.traverse(mapper);
+    rootParser.nextToken(); // Advance to the first token
+
+    // Use the default deserializer for the concrete class
+    return delegateToDefaultDeserializer(rootParser, context, mapper.constructType(concreteClass));
+  }
+
+  /**
+   * Delegate deserialization to the default deserializer for the given concrete type.
+   *
+   * @param parser The JSON parser.
+   * @param context The deserialization context.
+   * @param concreteType The concrete type to deserialize into.
+   * @return The deserialized object.
+   * @throws IOException If an I/O error occurs.
+   */
+  private LLMModuleResult delegateToDefaultDeserializer(
+      JsonParser parser, DeserializationContext context, JavaType concreteType) throws IOException {
+    var defaultDeserializer = context.findRootValueDeserializer(concreteType);
+    return (LLMModuleResult) defaultDeserializer.deserialize(parser, context);
   }
 }

orchestration/src/main/java/com/sap/ai/sdk/orchestration/client/model/DPIConfig.java

@@ -32,8 +32,9 @@
     value = "org.openapitools.codegen.languages.JavaClientCodegen",
     comments = "Generator version: 7.9.0")
 public class DPIConfig implements MaskingProviderConfig {
-  public static final String JSON_PROPERTY_TYPE = "type";
   private MethodEnum method;
+
+  public static final String JSON_PROPERTY_TYPE = "type";
   private TypeEnum type;
 
   /** Create a builder with no initialized field. */

orchestration/src/test/java/com/sap/ai/sdk/orchestration/LLMModuleResultDeserializerTest.java

@@ -0,0 +1,95 @@
+package com.sap.ai.sdk.orchestration;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.sap.ai.sdk.orchestration.client.model.LLMModuleResult;
+import com.sap.ai.sdk.orchestration.client.model.LLMModuleResultStreaming;
+import com.sap.ai.sdk.orchestration.client.model.LLMModuleResultSynchronous;
+import lombok.SneakyThrows;
+import org.junit.jupiter.api.Test;
+
+class LLMModuleResultDeserializerTest {
+
+  private final ObjectMapper objectMapper = OrchestrationClient.JACKSON;
+  private final String jsonTemplate =
+      """
+      {
+        "object": "chat.completion",
+        "id": "chatcmpl-12345",
+        "created": 1234567890,
+        "model": "gpt-3.5-turbo",
+        "choices": %s,
+        "usage": {
+          "completion_tokens": 10,
+          "prompt_tokens": 20,
+          "total_tokens": 30
+        }
+      }
+      """;
+
+  @SneakyThrows
+  @Test
+  void testSubtypeResolutionSynchronous() {
+
+    var choices =
+        """
+        [
+          {
+            "index": 0,
+            "message": {
+              "role": "assistant",
+              "content": "Sample response content."
+            },
+            "finish_reason": "length"
+          }
+        ]
+        """;
+
+    var json = String.format(jsonTemplate, choices);
+
+    // Deserialize JSON content
+    LLMModuleResult result = objectMapper.readValue(json, LLMModuleResult.class);
+
+    // Assert
+    assertThat(result).isExactlyInstanceOf(LLMModuleResultSynchronous.class);
+  }
+
+  @SneakyThrows
+  @Test
+  void testSubtypeResolutionStreaming() {
+    var choices =
+        """
+          [
+             {
+               "index": 0,
+               "delta": {
+                 "content": "Sample response content."
+               }
+             }
+           ]
+        """;
+
+    var json = String.format(jsonTemplate, choices);
+
+    // Deserialize JSON content
+    LLMModuleResult result = objectMapper.readValue(json, LLMModuleResult.class);
+
+    // Assert
+    assertThat(result).isExactlyInstanceOf(LLMModuleResultStreaming.class);
+  }
+
+  @SneakyThrows
+  @Test
+  void testSubtypeResolutionEmptyChoices() {
+
+    String choice = "[]";
+    var json = String.format(jsonTemplate, choice);
+
+    // Deserialize JSON content
+    LLMModuleResult result = objectMapper.readValue(json, LLMModuleResult.class);
+
+    // Assert
+    assertThat(result).isExactlyInstanceOf(LLMModuleResultSynchronous.class);
+  }
+}