Add some level of synchronization to the root of the API

src/main/java/org/kohsuke/github/GHCommitPointer.java

@@ -39,7 +39,8 @@ public class GHCommitPointer {
      * This points to the user who owns
      * the {@link #getRepository()}.
      */
-    public GHUser getUser() {
+    public GHUser getUser() throws IOException {
+        if (user != null) return user.root.getUser(user.getLogin());
         return user;
     }
 

src/main/java/org/kohsuke/github/GHCommitStatus.java

@@ -1,5 +1,6 @@
 package org.kohsuke.github;
 
+import java.io.IOException;
 import java.net.URL;
 
 /**
@@ -45,7 +46,8 @@ public String getDescription() {
         return description;
     }
 
-    public GHUser getCreator() {
+    public GHUser getCreator() throws IOException {
+        if (creator != null) return creator.root.getUser(creator.getLogin());
         return creator;
     }
 

src/main/java/org/kohsuke/github/GHDeployment.java

@@ -1,6 +1,6 @@
 package org.kohsuke.github;
 
-
+import java.io.IOException;
 import java.net.URL;
 
 public class GHDeployment extends GHObject {
@@ -41,7 +41,8 @@ public String getPayload() {
     public String getEnvironment() {
         return environment;
     }
-    public GHUser getCreator() {
+    public GHUser getCreator() throws IOException {
+        if(creator != null) return root.getUser(creator.getLogin());
         return creator;
     }
     public String getRef() {

src/main/java/org/kohsuke/github/GHGist.java

@@ -38,8 +38,8 @@ public class GHGist extends GHObject {
     /**
      * User that owns this Gist.
      */
-    public GHUser getOwner() {
-        return owner;
+    public GHUser getOwner() throws IOException {
+        return root.getUser(owner.getLogin());
     }
 
     public String getForksUrl() {

src/main/java/org/kohsuke/github/GHIssue.java

@@ -288,7 +288,8 @@ protected String getIssuesApiRoute() {
         return "/repos/"+owner.getOwnerName()+"/"+owner.getName()+"/issues/"+number;
     }
 
-    public GHUser getAssignee() {
+    public GHUser getAssignee() throws IOException {
+        if (assignee != null) return owner.root.getUser(assignee.getLogin());
         return assignee;
     }
 
@@ -299,8 +300,8 @@ public List<GHUser> getAssignees() {
     /**
      * User who submitted the issue.
      */
-    public GHUser getUser() {
-        return user;
+    public GHUser getUser() throws IOException {
+        return owner.root.getUser(user.getLogin());
     }
 
     /**
@@ -311,9 +312,9 @@ public GHUser getUser() {
      * even for an issue that's already closed. See
      * https://github.com/kohsuke/github-api/issues/60.
      */
-    public GHUser getClosedBy() {
+    public GHUser getClosedBy() throws IOException {
         if(!"closed".equals(state)) return null;
-        if(closed_by != null) return closed_by;
+        if(closed_by != null) return owner.root.getUser(closed_by.getLogin());;
 
         //TODO closed_by = owner.getIssue(number).getClosed_by();
         return closed_by;

src/main/java/org/kohsuke/github/GHMilestone.java

@@ -27,8 +27,8 @@ public GHRepository getOwner() {
         return owner;
     }
 
-    public GHUser getCreator() {
-        return creator;
+    public GHUser getCreator() throws IOException {
+        return root.getUser(creator.getLogin());
     }
 
     public Date getDueOn() {

src/main/java/org/kohsuke/github/GHPullRequest.java

@@ -200,7 +200,7 @@ public String getMergeCommitSha() throws IOException {
      * Depending on the original API call where this object is created, it may not contain everything.
      */
     private void populate() throws IOException {
-        if (merged_by!=null)    return; // already populated
+        if (mergeable_state!=null)    return; // already populated
         if (root.isOffline()) {
             return; // cannot populate, will have to live with what we have
         }

src/main/java/org/kohsuke/github/GitHub.java

@@ -47,6 +47,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TimeZone;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.logging.Logger;
 import javax.annotation.CheckForNull;
 import javax.annotation.Nonnull;
@@ -79,9 +80,10 @@ public class GitHub {
      */
     /*package*/ final String encodedAuthorization;
 
-    private final Map<String,GHUser> users = new Hashtable<String, GHUser>();
-    private final Map<String,GHOrganization> orgs = new Hashtable<String, GHOrganization>();
-
+    private final Map<String,GHUser> users;
+    private final Map<String,GHOrganization> orgs;
+    // Cache of myself object.
+    private GHMyself myself;
     private final String apiUrl;
 
     /*package*/ final RateLimitHandler rateLimitHandler;
@@ -146,6 +148,8 @@ public class GitHub {
             }
         }
 
+        users = new ConcurrentHashMap<String, GHUser>();
+        orgs = new ConcurrentHashMap<String, GHOrganization>();
         this.rateLimitHandler = rateLimitHandler;
         this.abuseLimitHandler = abuseLimitHandler;
 
@@ -264,7 +268,7 @@ public String getApiUrl() {
     /**
      * Sets the custom connector used to make requests to GitHub.
      */
-    public void setConnector(HttpConnector connector) {
+    public synchronized void setConnector(HttpConnector connector) {
         this.connector = connector;
     }
 
@@ -357,13 +361,15 @@ public GHRateLimit rateLimit() throws IOException {
     @WithBridgeMethods(GHUser.class)
     public GHMyself getMyself() throws IOException {
         requireCredential();
+        synchronized (this) {
+            if (this.myself != null) return myself;
+
+            GHMyself u = retrieve().to("/user", GHMyself.class);
 
-        GHMyself u = retrieve().to("/user", GHMyself.class);
-
-        u.root = this;
-        users.put(u.getLogin(), u);
-
-        return u;
+            u.root = this;
+            this.myself = u;
+            return u;
+        }
     }
 
     /**
@@ -379,7 +385,7 @@ public GHUser getUser(String login) throws IOException {
         return u;
     }
 
-
+    
     /**
      * clears all cached data in order for external changes (modifications and del
      */