Allow non-null but empty Parameters object in inference response (#11)

So far, kserve-client can only deserialize `parameters: null` or a
`parameters: { ... }` object (with all its fields filled) from an
inference response.

However, some KServe InferenceServices return `parameters: {}` as part
of an inference response. This case should also be accepted as a valid
response.

build.gradle.kts

@@ -37,6 +37,7 @@ dependencies {
 
     val junitVersion: String by project
     testImplementation(group = "org.junit.jupiter", name = "junit-jupiter-api", version = junitVersion)
+    testImplementation(group = "org.junit.jupiter", name = "junit-jupiter-params", version = junitVersion)
     testRuntimeOnly(group = "org.junit.jupiter", name = "junit-jupiter-engine", version = junitVersion)
     testImplementation(group = "org.assertj", name = "assertj-core", version = "3.25.1")
     testImplementation(group = "com.squareup.okhttp3", name = "mockwebserver", version = okHttpVersion)

src/main/java/com/bakdata/kserve/predictv2/Parameters.java

@@ -1,7 +1,7 @@
 /*
  * MIT License
  *
- * Copyright (c) 2022 bakdata
+ * Copyright (c) 2024 bakdata GmbH
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -24,15 +24,19 @@
 
 package com.bakdata.kserve.predictv2;
 
+import lombok.AllArgsConstructor;
 import lombok.Builder;
 import lombok.Data;
+import lombok.NoArgsConstructor;
 
 /**
- * A class to represent <a href="https://kserve.github.io/website/modelserving/inference_api/#parameters">
- *     parameters as defined in the v2 prediction protocol</a>.
+ * A class to represent <a href="https://kserve.github.io/website/modelserving/inference_api/#parameters"> parameters as
+ * defined in the v2 prediction protocol</a>.
  */
 @Data
 @Builder
+@NoArgsConstructor
+@AllArgsConstructor
 public class Parameters {
     private String contentType;
     private Object extra;

src/test/java/com/bakdata/kserve/predictv2/InferenceResponseTest.java

@@ -0,0 +1,64 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2024 bakdata GmbH
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.bakdata.kserve.predictv2;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import java.io.IOException;
+import org.assertj.core.api.SoftAssertions;
+import org.assertj.core.api.junit.jupiter.InjectSoftAssertions;
+import org.assertj.core.api.junit.jupiter.SoftAssertionsExtension;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+@ExtendWith(SoftAssertionsExtension.class)
+public class InferenceResponseTest {
+    private ObjectMapper objectMapper;
+
+    @InjectSoftAssertions
+    private SoftAssertions softly;
+
+    @BeforeEach
+    void setUpObjectMapper() {
+        this.objectMapper = new ObjectMapper()
+                .setPropertyNamingStrategy(PropertyNamingStrategies.SNAKE_CASE);
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {
+            "json_inference_responses/parameters_null.json",
+            "json_inference_responses/parameters_empty.json"
+    })
+    void shouldDeserialize(String jsonFilePath) throws IOException {
+        byte[] resourceFileBytes = getClass().getClassLoader().getResourceAsStream(jsonFilePath).readAllBytes();
+        String jsonInferenceResponse = new String(resourceFileBytes);
+
+        this.softly.assertThatCode(() -> {
+            this.objectMapper.readValue(jsonInferenceResponse, InferenceResponse.class);
+        }).doesNotThrowAnyException();
+    }
+}

src/test/resources/json_inference_responses/parameters_empty.json

@@ -0,0 +1,19 @@
+{
+  "model_name": "fake-model-name",
+  "model_version": "1.0.0",
+  "id": "d26ad6e7-0cd7-4f37-b463-0409d9246b43",
+  "parameters": {},
+  "outputs": [
+    {
+      "name": "fake-output-name",
+      "shape": [
+        1
+      ],
+      "datatype": "object",
+      "parameters": null,
+      "data": {
+        "output": "fake output"
+      }
+    }
+  ]
+}

src/test/resources/json_inference_responses/parameters_null.json

@@ -0,0 +1,19 @@
+{
+  "model_name": "fake-model-name",
+  "model_version": "1.0.0",
+  "id": "d26ad6e7-0cd7-4f37-b463-0409d9246b43",
+  "parameters": null,
+  "outputs": [
+    {
+      "name": "fake-output-name",
+      "shape": [
+        1
+      ],
+      "datatype": "object",
+      "parameters": null,
+      "data": {
+        "output": "fake output"
+      }
+    }
+  ]
+}