Do not put texture-less profiles on player heads

src/main/java/world/bentobox/bentobox/util/heads/HeadCache.java

@@ -82,6 +82,30 @@ public HeadCache(String userName,
     // ---------------------------------------------------------------------
 
 
+    /**
+     * Checks if this cache holds a usable skin texture.
+     * <p>
+     * A profile that has a name and a UUID but no texture property is worse than no
+     * profile at all: the server resolves it against the Mojang session server every time
+     * the head is shown, which quickly earns an HTTP 429 and still renders a default skin.
+     *
+     * @return {@code true} if the cached profile has a skin texture.
+     * @since 3.22.3
+     */
+    public boolean hasTexture()
+    {
+        try
+        {
+            return this.playerProfile != null && this.playerProfile.getTextures().getSkin() != null;
+        }
+        catch (Exception e)
+        {
+            // Treat an unreadable profile as having no texture.
+            return false;
+        }
+    }
+
+
     /**
      * Returns a new Player head with a cached texture. Be AWARE, usage does not use clone
      * method. If for some reason item stack is stored directly, then use clone in return
@@ -94,8 +118,8 @@ public ItemStack getPlayerHead()
         ItemStack item = new ItemStack(Material.PLAYER_HEAD);
         SkullMeta meta = (SkullMeta) item.getItemMeta();
 
-        // Set correct Skull texture
-        if (meta != null && this.playerProfile != null)
+        // Set correct Skull texture. Only if the texture is actually known - see hasTexture.
+        if (meta != null && this.hasTexture())
         {
             try {
                 meta.setOwnerProfile(this.playerProfile);

src/main/java/world/bentobox/bentobox/util/heads/HeadGetter.java

@@ -176,11 +176,21 @@ private void runPlayerHeadGetter() {
                                     HeadGetter.createProfile(userName, userId, HeadGetter.getTextureFromUUID(userId)));
                         }
 
-                        // Save in cache
-                        HeadGetter.cachedHeads.put(userName, cache);
+                        // Save in cache. A failed lookup must not evict a texture we already
+                        // have, otherwise one rate-limited call costs a working head for the
+                        // whole cache period.
+                        HeadCache previous = HeadGetter.cachedHeads.get(userName);
+
+                        if (cache.hasTexture() || previous == null || !previous.hasTexture()) {
+                            HeadGetter.cachedHeads.put(userName, cache);
+                        } else {
+                            cache = previous;
+                        }
 
                         // Tell requesters the head came in, but only if the texture is usable.
-                        if (cache.playerProfile != null && HeadGetter.headRequesters.containsKey(userName)) {
+                        // Handing out a profile with no texture makes the server look it up at
+                        // Mojang every time the head is shown, which ends in HTTP 429s.
+                        if (cache.hasTexture() && HeadGetter.headRequesters.containsKey(userName)) {
                             for (HeadRequester req : HeadGetter.headRequesters.get(userName)) {
                                 elementEntry.getValue().setHead(cache.getPlayerHead());