Add fork branch sync

src/main/java/org/kohsuke/github/GHBranchSync.java

@@ -0,0 +1,58 @@
+package org.kohsuke.github;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+
+public class GHBranchSync extends GitHubInteractiveObject {
+
+    private GHRepository owner;
+
+    private String message;
+
+    @JsonProperty("merge_type")
+    private String mergeType;
+
+    @JsonProperty("base_branch")
+    private String baseBranch;
+
+    /**
+     * Gets owner.
+     *
+     * @return the repository that this branch is in.
+     */
+    @SuppressFBWarnings(value = { "EI_EXPOSE_REP" }, justification = "Expected behavior")
+    public GHRepository getOwner() {
+        return owner;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public String getMergeType() {
+        return mergeType;
+    }
+
+    public String getBaseBranch() {
+        return baseBranch;
+    }
+
+    @Override
+    public String toString() {
+        return "GHBranchSync{" + "message='" + message + '\'' + ", mergeType='" + mergeType + '\'' + ", baseBranch='"
+                + baseBranch + '\'' + '}';
+    }
+
+    /**
+     * Wrap.
+     *
+     * @param repo
+     *            the repo
+     * @return the GH branch sync
+     */
+    GHBranchSync wrap(GHRepository repo) {
+        this.owner = repo;
+        return this;
+    }
+
+}

src/main/java/org/kohsuke/github/GHRepository.java

@@ -1614,6 +1614,24 @@ public GHRepository fork() throws IOException {
         throw new IOException(this + " was forked but can't find the new repository");
     }
 
+    /**
+     * Sync this repository fork branch
+     *
+     * @param branch
+     *            the branch to sync
+     * @return The current repository
+     * @throws IOException
+     *             the io exception
+     */
+    public GHBranchSync sync(String branch) throws IOException {
+        return root().createRequest()
+                .method("POST")
+                .with("branch", branch)
+                .withUrlPath(getApiTailUrl("merge-upstream"))
+                .fetch(GHBranchSync.class)
+                .wrap(this);
+    }
+
     /**
      * Forks this repository into an organization.
      *

src/test/java/org/kohsuke/github/GHRepositoryTest.java

@@ -47,6 +47,36 @@ private GHRepository getRepository(GitHub gitHub) throws IOException {
         return gitHub.getOrganization("hub4j-test-org").getRepository("github-api");
     }
 
+    /**
+     * Test sync of fork
+     *
+     * @throws IOException
+     *             Signals that an I/O exception has occurred.
+     */
+    @Test
+    public void sync() throws IOException {
+        GHRepository r = getRepository();
+        GHBranchSync sync = r.sync("main");
+        assertThat(sync.getOwner().getFullName(), equalTo("hub4j-test-org/github-api"));
+        assertThat(sync.getMessage(), equalTo("Successfully fetched and fast-forwarded from upstream github-api:main"));
+        assertThat(sync.getMergeType(), equalTo("fast-forward"));
+        assertThat(sync.getBaseBranch(), equalTo("github-api:main"));
+    }
+
+    /**
+     * Test sync of repository not a fork
+     *
+     * @throws IOException
+     *             Signals that an I/O exception has occurred.
+     */
+    @Test(expected = HttpException.class)
+    public void syncNoFork() throws IOException {
+        GHRepository r = getRepository();
+        GHBranchSync sync = r.sync("main");
+        fail("Should have thrown an exception");
+
+    }
+
     /**
      * Test zipball.
      *

src/test/resources/org/kohsuke/github/GHRepositoryTest/wiremock/sync/__files/1-user.json

@@ -0,0 +1,33 @@
+{
+  "login": "bitwiseman",
+  "id": 1958953,
+  "node_id": "MDQ6VXNlcjE5NTg5NTM=",
+  "avatar_url": "https://avatars3.githubusercontent.com/u/1958953?v=4",
+  "gravatar_id": "",
+  "url": "https://api.github.com/users/bitwiseman",
+  "html_url": "https://github.com/bitwiseman",
+  "followers_url": "https://api.github.com/users/bitwiseman/followers",
+  "following_url": "https://api.github.com/users/bitwiseman/following{/other_user}",
+  "gists_url": "https://api.github.com/users/bitwiseman/gists{/gist_id}",
+  "starred_url": "https://api.github.com/users/bitwiseman/starred{/owner}{/repo}",
+  "subscriptions_url": "https://api.github.com/users/bitwiseman/subscriptions",
+  "organizations_url": "https://api.github.com/users/bitwiseman/orgs",
+  "repos_url": "https://api.github.com/users/bitwiseman/repos",
+  "events_url": "https://api.github.com/users/bitwiseman/events{/privacy}",
+  "received_events_url": "https://api.github.com/users/bitwiseman/received_events",
+  "type": "User",
+  "site_admin": false,
+  "name": "Liam Newman",
+  "company": "Cloudbees, Inc.",
+  "blog": "",
+  "location": "Seattle, WA, USA",
+  "email": "bitwiseman@gmail.com",
+  "hireable": null,
+  "bio": "https://twitter.com/bitwiseman",
+  "public_repos": 166,
+  "public_gists": 4,
+  "followers": 135,
+  "following": 9,
+  "created_at": "2012-07-11T20:38:33Z",
+  "updated_at": "2019-09-24T19:32:29Z"
+}

src/test/resources/org/kohsuke/github/GHRepositoryTest/wiremock/sync/__files/2-orgs_hub4j-test-org.json

@@ -0,0 +1,42 @@
+{
+  "login": "hub4j-test-org",
+  "id": 7544739,
+  "node_id": "MDEyOk9yZ2FuaXphdGlvbjc1NDQ3Mzk=",
+  "url": "https://api.github.com/orgs/hub4j-test-org",
+  "repos_url": "https://api.github.com/orgs/hub4j-test-org/repos",
+  "events_url": "https://api.github.com/orgs/hub4j-test-org/events",
+  "hooks_url": "https://api.github.com/orgs/hub4j-test-org/hooks",
+  "issues_url": "https://api.github.com/orgs/hub4j-test-org/issues",
+  "members_url": "https://api.github.com/orgs/hub4j-test-org/members{/member}",
+  "public_members_url": "https://api.github.com/orgs/hub4j-test-org/public_members{/member}",
+  "avatar_url": "https://avatars3.githubusercontent.com/u/7544739?v=4",
+  "description": null,
+  "is_verified": false,
+  "has_organization_projects": true,
+  "has_repository_projects": true,
+  "public_repos": 9,
+  "public_gists": 0,
+  "followers": 0,
+  "following": 0,
+  "html_url": "https://github.com/hub4j-test-org",
+  "created_at": "2014-05-10T19:39:11Z",
+  "updated_at": "2015-04-20T00:42:30Z",
+  "type": "Organization",
+  "total_private_repos": 0,
+  "owned_private_repos": 0,
+  "private_gists": 0,
+  "disk_usage": 132,
+  "collaborators": 0,
+  "billing_email": "kk@kohsuke.org",
+  "default_repository_permission": "none",
+  "members_can_create_repositories": false,
+  "two_factor_requirement_enabled": false,
+  "members_allowed_repository_creation_type": "none",
+  "plan": {
+    "name": "free",
+    "space": 976562499,
+    "private_repos": 0,
+    "filled_seats": 3,
+    "seats": 0
+  }
+}