adjusting getters return type (timols#330)

Author: wiliamjcj

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

@@ -251,15 +251,15 @@ public void setLabels(String[] labels) {
         this.labels = labels;
     }
 
-    public int getUpvotes() {
+    public Integer getUpvotes() {
         return upvotes;
     }
 
     public void setUpvotes(int upvotes) {
         this.upvotes = upvotes;
     }
 
-    public int getDownvotes() {
+    public Integer getDownvotes() {
         return downvotes;
     }
 
@@ -352,7 +352,7 @@ public Boolean isShouldRemoveSourceBranch() {
         return shouldRemoveSourceBranch;
     }
 
-    public boolean isForceRemoveSourceBranch() {
+    public Boolean isForceRemoveSourceBranch() {
         return forceRemoveSourceBranch;
     }