StashRepository: Use sort() method of the List (#178)

That's a Java 8 feature. An object can use the best sorting algorithm for
its actual class (ArrayList in this case).

src/main/java/stashpullrequestbuilder/stashpullrequestbuilder/StashRepository.java

@@ -20,7 +20,7 @@
 import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
@@ -171,7 +171,7 @@ Map<String, String> getAdditionalParameters(StashPullRequestResponseValue pullRe
         client.getPullRequestComments(owner, repositoryName, id);
 
     // Process newest comments last so they can override older comments
-    Collections.sort(comments);
+    comments.sort(Comparator.naturalOrder());
 
     Map<String, String> result = new TreeMap<>();
 
@@ -594,7 +594,7 @@ private boolean isBuildTarget(StashPullRequestResponseValue pullRequest) {
     }
 
     // Start with most recent comments
-    Collections.sort(comments, Collections.reverseOrder());
+    comments.sort(Comparator.reverseOrder());
 
     for (StashPullRequestComment comment : comments) {
       String content = comment.getText();