Added ability to compare commits

src/main/java/org/gitlab/api/GitlabAPI.java

@@ -1022,6 +1022,24 @@ public class GitlabAPI {
         return Arrays.asList(diffs);
     }
 
+
+    // List commit diffs for a project ID and two commit hashes
+    // GET /projects/:id/repository/compare
+    public GitlabCommitComparison compareCommits(Serializable projectId, String commitHash1, String commitHash2) throws IOException {
+        return compareCommits(projectId, commitHash1, commitHash2, new Pagination());
+    }
+
+    // List commit diffs for a project ID and two commit hashes
+    // GET /projects/:id/repository/compare
+    public GitlabCommitComparison compareCommits(Serializable projectId, String commitHash1, String commitHash2, Pagination pagination) throws IOException {
+        String tailUrl = GitlabProject.URL + "/" + sanitizeProjectId(projectId) + GitlabCommitComparison.URL;
+        Query query = new Query()
+                .append("from", commitHash1)
+                .append("to", commitHash2);
+        query.mergeWith(pagination.asQuery());
+        return retrieve().to(tailUrl + query, GitlabCommitComparison.class);
+    }
+
     // List commit statuses for a project ID and commit hash
     // GET /projects/:id/repository/commits/:sha/statuses
     public List<GitlabCommitStatus> getCommitStatuses(GitlabProject project, String commitHash) throws IOException {

src/main/java/org/gitlab/api/models/GitlabCommitComparison.java

+package org.gitlab.api.models;
+
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import java.util.List;
+
+public class GitlabCommitComparison {
+    public final static String URL = "/repository/compare";
+    @JsonProperty("commit")
+    private GitlabCommit commit;
+    @JsonProperty("commits")
+    private List<GitlabCommit> commits;
+    @JsonProperty("diffs")
+    private List<GitlabCommitDiff> diffs;
+    @JsonProperty("compare_same_ref")
+    private Boolean compareSameRef;
+    @JsonProperty("compare_timeout")
+    private Boolean compareTimeout;
+
+    public GitlabCommit getCommit() {
+        return commit;
+    }
+
+    public void setCommit(GitlabCommit commit) {
+        this.commit = commit;
+    }
+
+    public List<GitlabCommit> getCommits() {
+        return commits;
+    }
+
+    public void setCommits(List<GitlabCommit> commits) {
+        this.commits = commits;
+    }
+
+    public List<GitlabCommitDiff> getDiffs() {
+        return diffs;
+    }
+
+    public void setDiffs(List<GitlabCommitDiff> diffs) {
+        this.diffs = diffs;
+    }
+
+    public Boolean getCompareSameRef() {
+        return compareSameRef;
+    }
+
+    public void setCompareSameRef(Boolean compareSameRef) {
+        this.compareSameRef = compareSameRef;
+    }
+
+    public Boolean getCompareTimeout() {
+        return compareTimeout;
+    }
+
+    public void setCompareTimeout(Boolean compareTimeout) {
+        this.compareTimeout = compareTimeout;
+    }
+}