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/Participant.java

 package org.gitlab4j.api.models;
 
 public class Participant extends AbstractUser<Participant> {
-}
+    private static final long serialVersionUID = 1L;
\ No newline at end of file
+}

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

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

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

 package org.gitlab4j.api.models;
 
+import java.io.Serializable;
 import java.util.Date;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class Pipeline {
+public class Pipeline implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Long id;
     private Long iid;

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

 package org.gitlab4j.api.models;
 
-import java.util.Date;
-
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import org.gitlab4j.api.Constants.PipelineOrderBy;
 import org.gitlab4j.api.Constants.PipelineScope;
 import org.gitlab4j.api.Constants.SortOrder;
-import org.gitlab4j.api.utils.JacksonJson;
 import org.gitlab4j.api.GitLabApiForm;
+import org.gitlab4j.api.utils.JacksonJson;
 
-import com.fasterxml.jackson.annotation.JsonIgnore;
+import java.io.Serializable;
+import java.util.Date;
 
 /**
  *  This class is used to filter Pipelines when getting lists of them.
  */
-public class PipelineFilter {
+public class PipelineFilter implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     /** {@link org.gitlab4j.api.Constants.PipelineScope} The scope of pipelines, one of: running, pending, finished, branches, tags */
     private PipelineScope scope;
 
-    /** {@link org.gitlab4j.api.Constants.PipelineScope} The status of pipelines, one of: running, pending, success, failed, canceled, skipped, created */    
+    /** {@link org.gitlab4j.api.Constants.PipelineScope} The status of pipelines, one of: running, pending, success, failed, canceled, skipped, created */
     private PipelineStatus status;
 
     /** The ref of pipelines. */

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

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

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

 package org.gitlab4j.api.models;
 
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonValue;
 import org.gitlab4j.api.utils.JacksonJson;
 import org.gitlab4j.api.utils.JacksonJsonEnumHelper;
 
-import com.fasterxml.jackson.annotation.JsonCreator;
-import com.fasterxml.jackson.annotation.JsonValue;
+import java.io.Serializable;
 
-public class Position {
+public class Position implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     public static enum PositionType {
 

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

 
 package org.gitlab4j.api.models;
 
-import java.util.Date;
-import java.util.List;
-
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonValue;
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 import org.gitlab4j.api.Constants.AutoDevopsDeployStrategy;
 import org.gitlab4j.api.Constants.BuildGitStrategy;
 import org.gitlab4j.api.Constants.SquashOption;
@@ -12,11 +12,12 @@ import org.gitlab4j.api.models.ImportStatus.Status;
 import org.gitlab4j.api.utils.JacksonJson;
 import org.gitlab4j.api.utils.JacksonJsonEnumHelper;
 
-import com.fasterxml.jackson.annotation.JsonCreator;
-import com.fasterxml.jackson.annotation.JsonValue;
-import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import java.io.Serializable;
+import java.util.Date;
+import java.util.List;
 
-public class Project {
+public class Project implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     // Enum for the merge_method of the Project instance.
     public enum MergeMethod {

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

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

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

@@ -5,10 +5,13 @@ import com.fasterxml.jackson.annotation.JsonProperty;
 import org.gitlab4j.api.Constants;
 import org.gitlab4j.api.utils.JacksonJson;
 
+import java.io.Serializable;
 import java.util.Date;
 import java.util.List;
 
-public class ProjectAccessToken {
+public class ProjectAccessToken implements Serializable {
+    private static final long serialVersionUID = 1L;
+
     private Long userId;
     private List<Constants.ProjectAccessTokenScope> scopes;
     private String name;

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

@@ -4,7 +4,10 @@ import org.gitlab4j.api.GitLabApiForm;
 
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
-public class ProjectApprovalsConfig {
+import java.io.Serializable;
+
+public class ProjectApprovalsConfig implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Integer approvalsBeforeMerge;
     private Boolean resetApprovalsOnPush;

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

 package org.gitlab4j.api.models;
 
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+import org.gitlab4j.api.utils.JacksonJson;
+
+import java.io.Serializable;
 import java.util.Date;
 import java.util.List;
 
-import org.gitlab4j.api.utils.JacksonJson;
-
-import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+public class ProjectFetches implements Serializable {
+    private static final long serialVersionUID = 1L;
 
-public class ProjectFetches {
+    public static class DateCount implements Serializable {
 
-    public static class DateCount {
+        private static final long serialVersionUID = 1L;
 
         private Integer count;
 
@@ -33,7 +36,8 @@ public class ProjectFetches {
         }
     }
 
-    public static class Fetches {
+    public static class Fetches implements Serializable {
+        private static final long serialVersionUID = 1L;
 
         private Integer total;
         private List<DateCount> days;

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

 package org.gitlab4j.api.models;
 
-import java.util.Date;
-
 import org.gitlab4j.api.Constants;
 import org.gitlab4j.api.Constants.ProjectOrderBy;
 import org.gitlab4j.api.Constants.SortOrder;
-import org.gitlab4j.api.utils.JacksonJson;
 import org.gitlab4j.api.GitLabApiForm;
+import org.gitlab4j.api.utils.JacksonJson;
+
+import java.io.Serializable;
+import java.util.Date;
 
 /**
  *  This class is used to filter Projects when getting lists of projects for a specified user.
  */
-public class ProjectFilter {
+public class ProjectFilter implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Boolean archived;
     private Visibility visibility;

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

 package org.gitlab4j.api.models;
 
 public class ProjectGroup extends AbstractGroup<ProjectGroup> {
+    private static final long serialVersionUID = 1L;
 }

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

 package org.gitlab4j.api.models;
 
+import java.io.Serializable;
 import java.util.List;
 
 import org.gitlab4j.api.GitLabApiForm;
@@ -7,7 +8,8 @@ import org.gitlab4j.api.GitLabApiForm;
 /**
  *  This class is used to filter Groups when getting lists of groups for a specified project.
  */
-public class ProjectGroupsFilter {
+public class ProjectGroupsFilter implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private String search;
     private AccessLevel sharedMinAccessLevel;

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

 
 package org.gitlab4j.api.models;
 
-import java.util.Date;
-
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class ProjectHook {
+import java.io.Serializable;
+import java.util.Date;
+
+public class ProjectHook implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Boolean buildEvents;
     private Date createdAt;

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

@@ -3,12 +3,15 @@ package org.gitlab4j.api.models;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
+import java.io.Serializable;
+
 /**
  * This class contains the sizing information from the project. To get this information,
  * ProjectApi.getProject() has to be called with parameter statistics=true
  * which is only allowed for GitLab admins.
  */
-public class ProjectStatistics {
+public class ProjectStatistics implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     long commitCount;
     long storageSize;

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

 package org.gitlab4j.api.models;
 
 public class ProjectUser extends AbstractUser<ProjectUser> {
+    private static final long serialVersionUID = 1L;
 }

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

 
 package org.gitlab4j.api.models;
 
+import java.io.Serializable;
 import java.util.List;
 
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class ProtectedBranch {
+public class ProtectedBranch implements Serializable {
+    private static final long serialVersionUID = 1L;
 
     private Long id;
     private String name;

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

 package org.gitlab4j.api.models;
 
-import java.util.List;
-
 import org.gitlab4j.api.utils.JacksonJson;
 
-public class ProtectedTag {
+import java.io.Serializable;
+import java.util.List;
+
+public class ProtectedTag implements Serializable {
+    private static final long serialVersionUID = 1L;
 
-    public static class CreateAccessLevel {
+    public static class CreateAccessLevel implements Serializable {
+        private static final long serialVersionUID = 1L;
 
         private AccessLevel access_level;
         private String accessLevelDescription;

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

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