Add implements Serializable to all model classes to support native image (GraalVM) (#1074)

---------

Co-authored-by: Jeremie Bresson <jeremie.bresson@unblu.com>

src/main/java/org/gitlab4j/api/models/TaskCompletionStatus.java

@@ -2,7 +2,10 @@ package org.gitlab4j.api.models;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class TaskCompletionStatus {
+import java.io.Serializable;
+
+public class TaskCompletionStatus implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Integer count;
     private Integer completedCount;

src/main/java/org/gitlab4j/api/models/TimeStats.java

@@ -2,7 +2,10 @@ package org.gitlab4j.api.models;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class TimeStats {
+import java.io.Serializable;
+
+public class TimeStats implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Integer timeEstimate;
     private Integer totalTimeSpent;

src/main/java/org/gitlab4j/api/models/Todo.java

 package org.gitlab4j.api.models;
 
-import java.io.IOException;
-import java.util.Date;
-
-import org.gitlab4j.api.Constants.TodoAction;
-import org.gitlab4j.api.Constants.TodoState;
-import org.gitlab4j.api.Constants.TodoType;
-import org.gitlab4j.api.utils.JacksonJson;
-
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.core.JsonProcessingException;
@@ -16,8 +8,17 @@ import com.fasterxml.jackson.databind.JsonDeserializer;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.gitlab4j.api.Constants.TodoAction;
+import org.gitlab4j.api.Constants.TodoState;
+import org.gitlab4j.api.Constants.TodoType;
+import org.gitlab4j.api.utils.JacksonJson;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.util.Date;
 
-public class Todo {
+public class Todo implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Long id;
     private Project project;

src/main/java/org/gitlab4j/api/models/Topic.java

@@ -2,7 +2,10 @@ package org.gitlab4j.api.models;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class Topic {
+import java.io.Serializable;
+
+public class Topic implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Integer id;
 

src/main/java/org/gitlab4j/api/models/TopicParams.java

@@ -4,6 +4,7 @@ import org.gitlab4j.api.GitLabApiForm;
 import org.gitlab4j.api.TopicsApi;
 
 import java.io.File;
+import java.io.Serializable;
 
 /**
  * This class is utilized by the {@link TopicsApi#createTopic(TopicParams)}
@@ -12,7 +13,8 @@ import java.io.File;
  *
  * Avatar Upload has its own Upload in {@link TopicsApi#updateTopicAvatar(Integer,File)}
  */
-public class TopicParams {
+public class TopicParams implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private String name;
     private String title;

src/main/java/org/gitlab4j/api/models/TreeItem.java

@@ -2,7 +2,10 @@ package org.gitlab4j.api.models;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class TreeItem {
+import java.io.Serializable;
+
+public class TreeItem implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     public enum Type {
         TREE, BLOB, COMMIT;

src/main/java/org/gitlab4j/api/models/Trigger.java

 package org.gitlab4j.api.models;
 
+import java.io.Serializable;
 import java.util.Date;
 
-public class Trigger {
+public class Trigger implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Long id;
     private String description;

src/main/java/org/gitlab4j/api/models/User.java

 package org.gitlab4j.api.models;
 
+import org.gitlab4j.api.utils.JacksonJson;
+
 import java.util.Date;
 import java.util.List;
 
-import org.gitlab4j.api.utils.JacksonJson;
-
 public class User extends AbstractUser<User> {
+    private static final long serialVersionUID = 1L;
 
     private String bio;
     private Boolean bot;

src/main/java/org/gitlab4j/api/models/Variable.java

 package org.gitlab4j.api.models;
 
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Map;
-
-import org.gitlab4j.api.utils.JacksonJson;
-import org.gitlab4j.api.utils.JacksonJsonEnumHelper;
-
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonValue;
+import org.gitlab4j.api.utils.JacksonJson;
+import org.gitlab4j.api.utils.JacksonJsonEnumHelper;
+
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
 
-public class Variable {
+public class Variable implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     /**
      * Enum for the various Commit build status values.

src/main/java/org/gitlab4j/api/models/Version.java

@@ -2,7 +2,10 @@ package org.gitlab4j.api.models;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class Version {
+import java.io.Serializable;
+
+public class Version implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private String version;
     private String revision;

src/main/java/org/gitlab4j/api/models/WikiAttachment.java

@@ -2,9 +2,13 @@ package org.gitlab4j.api.models;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class WikiAttachment {
+import java.io.Serializable;
 
-    public static class Link {
+public class WikiAttachment implements Serializable {
+    private static final long serialVersionUID = 1L;
+
+    public static class Link implements Serializable {
+        private static final long serialVersionUID = 1L;
 
         private String url;
         private String markdown;
@@ -12,15 +16,15 @@ public class WikiAttachment {
         public String getUrl() {
             return url;
         }
-    
+
         public void setUrl(String url) {
             this.url = url;
         }
-    
+
         public String getMarkdown() {
             return markdown;
         }
-    
+
         public void setMarkdown(String markdown) {
             this.markdown = markdown;
         }

src/main/java/org/gitlab4j/api/models/WikiPage.java

@@ -25,7 +25,10 @@ package org.gitlab4j.api.models;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class WikiPage {
+import java.io.Serializable;
+
+public class WikiPage implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private String title;
     private String content;

src/main/java/org/gitlab4j/api/services/NotificationService.java

 package org.gitlab4j.api.services;
 
+import java.io.Serializable;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
@@ -9,7 +10,8 @@ import org.gitlab4j.api.utils.JacksonJson;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
-public abstract class NotificationService {
+public abstract class NotificationService implements Serializable{
+    private static final long serialVersionUID = 1L;
 
     public static final String NOTIFY_ONLY_BROKEN_PIPELINES_PROP = "notify_only_broken_pipelines";
     public static final String NOTIFY_ONLY_DEFAULT_BRANCH_PROP = "notify_only_default_branch";

src/main/java/org/gitlab4j/api/services/SlackService.java

@@ -5,7 +5,8 @@ import org.gitlab4j.api.GitLabApiForm;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
 public class SlackService extends NotificationService {
-    
+    private static final long serialVersionUID = 1L;
+
     private String defaultChannel;
 
     /**

src/main/java/org/gitlab4j/api/webhook/ExternalStatusCheckEvent.java

 package org.gitlab4j.api.webhook;
 
+import java.io.Serializable;
 import java.util.List;
 
 import org.gitlab4j.api.models.Assignee;
@@ -7,7 +8,8 @@ import org.gitlab4j.api.models.User;
 import org.gitlab4j.api.utils.JacksonJson;
 import org.gitlab4j.api.webhook.MergeRequestEvent.ObjectAttributes;
 
-public class ExternalStatusCheckEvent {
+public class ExternalStatusCheckEvent implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private String objectKind;
     private String eventType;

src/test/java/org/gitlab4j/api/JsonUtils.java

 package org.gitlab4j.api;
 
+import static org.junit.jupiter.api.Assertions.fail;
+
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.Reader;
+import java.io.Serializable;
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.Collection;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 import org.gitlab4j.api.utils.JacksonJson;
+import org.junit.jupiter.api.Assertions;
 
 import com.fasterxml.jackson.core.JsonParseException;
 import com.fasterxml.jackson.core.JsonProcessingException;
@@ -26,7 +37,7 @@ public class JsonUtils {
     }
 
     static JsonNode readTreeFromMap(Map<String, Object> map) throws JsonParseException, JsonMappingException, IOException {
-	String jsonString = jacksonJson.getObjectMapper().writeValueAsString(map);
+        String jsonString = jacksonJson.getObjectMapper().writeValueAsString(map);
         return (jacksonJson.readTree(jsonString));
     }
     
@@ -40,48 +51,120 @@ public class JsonUtils {
     }
 
     static <T> T unmarshalResource(Class<T> returnType, String filename) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         InputStreamReader reader = new InputStreamReader(TestGitLabApiBeans.class.getResourceAsStream(filename));
         return (jacksonJson.unmarshal(returnType, reader));
     }
 
-    static <T> List<T> unmarshalResourceList(Class<T> returnType,  String filename) throws JsonParseException, JsonMappingException, IOException {
+    static <T> List<T> unmarshalResourceList(Class<T> returnType, String filename) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         InputStreamReader reader = new InputStreamReader(TestGitLabApiBeans.class.getResourceAsStream(filename));
         return (JsonUtils.unmarshalList(returnType, reader));
     }
 
     static <T> Map<String, T> unmarshalResourceMap(Class<T> returnType, String filename) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         InputStreamReader reader = new InputStreamReader(TestGitLabApiBeans.class.getResourceAsStream(filename));
         return (jacksonJson.unmarshalMap(returnType, reader));
     }
 
     static <T> T unmarshal(Class<T> returnType, Reader reader) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         return (jacksonJson.unmarshal(returnType, reader));
     }
 
     static <T> T unmarshal(Class<T> returnType, JsonNode tree) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         return (jacksonJson.unmarshal(returnType, tree));
     }
 
     static <T> T unmarshal(Class<T> returnType, String json) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         return (jacksonJson.unmarshal(returnType, json));
     }
 
     static <T> List<T> unmarshalList(Class<T> returnType, Reader reader) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         return (jacksonJson.unmarshalList(returnType, reader));
     }
 
     static <T> List<T> unmarshalList(Class<T> returnType, String json) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         return (jacksonJson.unmarshalList(returnType, json));
     }
 
     static <T> Map<String, T> unmarshalMap(Class<T> returnType, Reader reader) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         return (jacksonJson.unmarshalMap(returnType, reader));
     }
 
     static <T> Map<String, T> unmarshalMap(Class<T> returnType, String json) throws JsonParseException, JsonMappingException, IOException {
+        checkSerializable(returnType);
         return (jacksonJson.unmarshalMap(returnType, json));
     }
 
+    static <T> void checkSerializable(Class<T> cls) {
+        if(!isSerializable(cls, new HashSet<>())) {
+            fail("Class " + cls.getCanonicalName() + " or one of its member does not implement Serializable");
+        }
+    }
+    static <T> boolean isSerializable(Class<T> cls, Set<Class<?>> checkedTypes) {
+        if (checkedTypes.contains(cls)) {
+            return true;
+        }
+        checkedTypes.add(cls);
+
+        if (!Serializable.class.isAssignableFrom(cls)) {
+            return false;
+        }
+
+        Field[] fields = cls.getDeclaredFields();
+        for (Field field : fields) {
+            if (!Modifier.isStatic(field.getModifiers()) && !Modifier.isTransient(field.getModifiers())) {
+                Class<?> fieldClass = field.getType();
+                if (!isSimpleType(fieldClass) && !isSerializable(fieldClass, checkedTypes) && !isCollectionSerializable(field, checkedTypes)) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    private static boolean isSimpleType(Class<?> type) {
+        return type.isPrimitive() ||
+               type.equals(String.class) ||
+               type.equals(Integer.class) ||
+               type.equals(Long.class) ||
+               type.equals(Double.class) ||
+               type.equals(Float.class) ||
+               type.equals(Boolean.class) ||
+               type.equals(Character.class) ||
+               type.equals(Byte.class) ||
+               type.equals(Short.class);
+    }
+    
+    private static boolean isCollectionSerializable(Field field, Set<Class<?>> checkedTypes) {
+        Class<?> fieldType = field.getType();
+        if (Collection.class.isAssignableFrom(fieldType) || Map.class.isAssignableFrom(fieldType)) {
+            Type genericType = field.getGenericType();
+
+            if (genericType instanceof ParameterizedType) {
+                ParameterizedType parameterizedType = (ParameterizedType) genericType;
+                Type[] typeArguments = parameterizedType.getActualTypeArguments();
+
+                for (Type typeArg : typeArguments) {
+                    if (typeArg instanceof Class) {
+                        Class<?> typeClass = (Class<?>) typeArg;
+                        if (!isSimpleType(typeClass) && !isSerializable(typeClass, checkedTypes)) {
+                            return false;
+                        }
+                    }
+                }
+            }
+        }
+        return true;
+    }
+
     static <T> boolean compareJson(T apiObject, String filename) throws IOException {
         InputStreamReader reader = new InputStreamReader(TestGitLabApiBeans.class.getResourceAsStream(filename));
         return (compareJson(apiObject, reader));