Show alex or steve portrait for offline account

HMCLCore/src/main/java/org/jackhuang/hmcl/auth/Account.java

@@ -20,6 +20,7 @@ package org.jackhuang.hmcl.auth;
 import java.net.Proxy;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.UUID;
 
 /**
  *
@@ -32,6 +33,11 @@ public abstract class Account {
      */
     public abstract String getUsername();
 
+    /**
+     * @return the UUID
+     */
+    public abstract UUID getUUID();
+
     /**
      * log in.
      * @param selector selects a character

HMCLCore/src/main/java/org/jackhuang/hmcl/auth/OfflineAccount.java

@@ -20,10 +20,12 @@ package org.jackhuang.hmcl.auth;
 import org.jackhuang.hmcl.util.Lang;
 import org.jackhuang.hmcl.util.Pair;
 import org.jackhuang.hmcl.util.StringUtils;
+import org.jackhuang.hmcl.util.UUIDTypeAdapter;
 
 import java.net.Proxy;
 import java.util.Map;
 import java.util.Objects;
+import java.util.UUID;
 
 /**
  *
@@ -45,8 +47,8 @@ public class OfflineAccount extends Account {
             throw new IllegalArgumentException("Username cannot be blank");
     }
 
-    public String getUuid() {
-        return uuid;
+    public UUID getUUID() {
+        return UUIDTypeAdapter.fromString(uuid);
     }
 
     @Override

HMCLCore/src/main/java/org/jackhuang/hmcl/auth/yggdrasil/YggdrasilAccount.java

@@ -244,6 +244,13 @@ public final class YggdrasilAccount extends Account {
         }
     }
 
+    public UUID getUUID() {
+        if (getSelectedProfile() == null)
+            return null;
+        else
+            return getSelectedProfile().getId();
+    }
+
     public Optional<ProfileTexture> getSkin(GameProfile profile) throws IOException, JsonParseException {
         if (StringUtils.isBlank(userId))
             throw new IllegalStateException("Not logged in");