get all merge requests for a group (#932)

Co-authored-by: Erkan <erkanerkisi>

src/main/java/org/gitlab4j/api/MergeRequestApi.java

@@ -85,20 +85,22 @@ public class MergeRequestApi extends AbstractApi {
      *
      * @param filter a MergeRequestFilter instance with the filter settings
      * @param itemsPerPage the number of MergeRequest instances that will be fetched per page
-     * @return all merge requests for the specified project matching the filter
+     * @return all merge requests for the specified project/group matching the filter
      * @throws GitLabApiException if any exception occurs
      */
     public Pager<MergeRequest> getMergeRequests(MergeRequestFilter filter, int itemsPerPage) throws GitLabApiException {
 
         MultivaluedMap<String, String> queryParams = (filter != null ? filter.getQueryParams().asMap() : null);
-        if (filter != null && (filter.getProjectId() != null && filter.getProjectId().intValue() > 0) ||
-                (filter.getIids() != null && filter.getIids().size() > 0)) {
+        if (filter != null && ((filter.getProjectId() != null && filter.getProjectId().intValue() > 0) ||
+                (filter.getIids() != null && filter.getIids().size() > 0))) {
 
             if (filter.getProjectId() == null || filter.getProjectId().intValue() == 0) {
                 throw new RuntimeException("project ID cannot be null or 0");
             }
 
             return (new Pager<MergeRequest>(this, MergeRequest.class, itemsPerPage, queryParams, "projects", filter.getProjectId(), "merge_requests"));
+        } else if (filter != null && filter.getGroupId() != null && filter.getGroupId().intValue() > 0) {
+            return (new Pager<MergeRequest>(this, MergeRequest.class, itemsPerPage, queryParams, "groups", filter.getGroupId(), "merge_requests"));
         } else {
             return (new Pager<MergeRequest>(this, MergeRequest.class, itemsPerPage, queryParams, "merge_requests"));
         }

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

@@ -22,6 +22,7 @@ import com.fasterxml.jackson.annotation.JsonIgnore;
 public class MergeRequestFilter {
 
     private Long projectId;
+    private Long groupId;
     private List<Long> iids;
     private MergeRequestState state;
     private MergeRequestOrderBy orderBy;
@@ -315,6 +316,19 @@ public class MergeRequestFilter {
         this.wip = wip;
     }
 
+    public Long getGroupId() {
+        return groupId;
+    }
+
+    public void setGroupId(Long groupId) {
+        this.groupId = groupId;
+    }
+
+    public MergeRequestFilter withGroupId(Long groupId) {
+        this.groupId = groupId;
+        return (this);
+    }
+
     public MergeRequestFilter withWip(Boolean wip) {
         this.wip = wip;
         return (this);