Use un-synchronized Collections instead of Java2 Vector

The result objects returned by the proxy don't need to be synchronized.
However, the Vector class is fully synchronized for backwards 
compatibility (it's around since Java 2). This change uses the more
lightweight ArrayList, and the Collections.emptyList() singleton where
applicable.

Author: oxc

src/main/java/com/dkaedv/glghproxy/controller/OrgsController.java

@@ -1,8 +1,8 @@
 package com.dkaedv.glghproxy.controller;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.List;
-import java.util.Vector;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -29,6 +29,6 @@ public List<Repository> getReposForOrg(
 
 		LOG.info("Received request: orgname=" + orgname + ", per_page=" + per_page + ", page=" + page + ", authorization=" + authorization);
 
-		return new Vector<Repository>();
+		return Collections.emptyList();
 	}
 }

src/main/java/com/dkaedv/glghproxy/controller/ReposController.java

@@ -1,8 +1,8 @@
 package com.dkaedv.glghproxy.controller;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.List;
-import java.util.Vector;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -96,7 +96,7 @@ public List<Event> getEvents(
 			@RequestHeader("Authorization") String authorization
 			) {
 
-		return new Vector<Event>();
+		return Collections.emptyList();
 	}
 
 	@RequestMapping("/{namespace}/{repo}/pulls")
@@ -180,7 +180,7 @@ public List<Comment> getReviewCommentsOnPullRequest(
 			@RequestHeader("Authorization") String authorization
 			) throws IOException {
 
-		return new Vector<Comment>();
+		return Collections.emptyList();
 	}
 
 	@RequestMapping(value = "/{namespace}/{repo}/hooks", method = RequestMethod.GET)

src/main/java/com/dkaedv/glghproxy/controller/UserController.java

@@ -1,8 +1,8 @@
 package com.dkaedv.glghproxy.controller;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.List;
-import java.util.Vector;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -27,7 +27,7 @@ public List<Repository> getReposForCurrentUser(
 
 		LOG.info("Received request: per_page=" + per_page + ", page=" + page);
 
-		return new Vector<Repository>();
+		return Collections.emptyList();
 	}
 
 }

src/main/java/com/dkaedv/glghproxy/converter/GitlabToGithubConverter.java

@@ -1,8 +1,8 @@
 package com.dkaedv.glghproxy.converter;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
-import java.util.Vector;
 
 import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.logging.Log;
@@ -49,7 +49,7 @@ public static RepositoryBranch convertBranch(GitlabBranch glbranch) {
 	}
 
 	public static List<RepositoryBranch> convertBranches(List<GitlabBranch> glbranches) {
-		List<RepositoryBranch> branches = new Vector<RepositoryBranch>();
+		List<RepositoryBranch> branches = new ArrayList<>(glbranches.size());
 
 		for (GitlabBranch glbranch : glbranches) {
 			RepositoryBranch branch = convertBranch(glbranch);
@@ -81,9 +81,10 @@ public static RepositoryCommit convertCommit(GitlabCommit glcommit, List<GitlabC
 		repoCommit.setAuthor(user);
 		repoCommit.setCommitter(user);
 
-		if (glcommit.getParentIds() != null) {
-			List<Commit> parents = new Vector<Commit>();
-			for (String parentSha : glcommit.getParentIds()) {
+		List<String> parentIds = glcommit.getParentIds();
+		if (parentIds != null) {
+			List<Commit> parents = new ArrayList<>(parentIds.size());
+			for (String parentSha : parentIds) {
 				Commit parent = new Commit();
 				parent.setSha(parentSha);
 				parents.add(parent);
@@ -92,7 +93,7 @@ public static RepositoryCommit convertCommit(GitlabCommit glcommit, List<GitlabC
 		}
 
 		if (gldiffs != null) {
-			List<CommitFile> files = new Vector<CommitFile>();
+			List<CommitFile> files = new ArrayList<>(gldiffs.size());
 			for (GitlabCommitDiff diff : gldiffs) {
 				convertCommitFile(files, diff);
 			}
@@ -159,7 +160,7 @@ public static Repository convertRepository(GitlabProject project) {
 	}
 
 	public static List<Repository> convertRepositories(List<GitlabProject> projects) {
-		List<Repository> repos = new Vector<Repository>();
+		List<Repository> repos = new ArrayList<>(projects.size());
 
 		for (GitlabProject project : projects) {
 			repos.add(convertRepository(project));
@@ -169,7 +170,7 @@ public static List<Repository> convertRepositories(List<GitlabProject> projects)
 	}
 
 	public static List<PullRequest> convertMergeRequests(List<GitlabMergeRequest> glmergerequests, String gitlabUrl, String namespace, String repo) {
-		List<PullRequest> pulls = new Vector<PullRequest>();
+		List<PullRequest> pulls = new ArrayList<>(glmergerequests.size());
 
 		for (GitlabMergeRequest glmr : glmergerequests) {
 			pulls.add(convertMergeRequest(glmr, gitlabUrl, namespace, repo));
@@ -282,7 +283,7 @@ public static User convertUser(GitlabUser gluser) {
 	}
 
 	public static List<RepositoryCommit> convertCommits(List<GitlabCommit> glcommits) {
-		List<RepositoryCommit> commits = new Vector<RepositoryCommit>();
+		List<RepositoryCommit> commits = new ArrayList<>(glcommits.size());
 
 		for (GitlabCommit glcommit : glcommits) {
 			commits.add(convertCommit(glcommit, null, null));
@@ -292,7 +293,7 @@ public static List<RepositoryCommit> convertCommits(List<GitlabCommit> glcommits
 	}
 
 	public static List<Comment> convertComments(List<GitlabNote> glnotes) {
-		List<Comment> comments = new Vector<Comment>();
+		List<Comment> comments = new ArrayList<>(glnotes.size());
 
 		for (GitlabNote glnote : glnotes) {
 			comments.add(convertComment(glnote));
@@ -313,7 +314,7 @@ private static Comment convertComment(GitlabNote glnote) {
 	}
 
 	public static List<RepositoryHook> convertHooks(List<GitlabProjectHook> glhooks) {
-		List<RepositoryHook> hooks = new Vector<RepositoryHook>();
+		List<RepositoryHook> hooks = new ArrayList<>(glhooks.size());
 
 		for (GitlabProjectHook glhook : glhooks) {
 			hooks.add(convertHook(glhook));