Fixed #3218

CHANGELOG.md

@@ -1,4 +1,5 @@
 # Table of contents
+- [Release Candidate 29 (TBD)](#release-candidate-29-tbd)
 - [Release Candidate 28 (06 Sep 2021)](#release-candidate-28-06-sep-2021)
 - [Release Candidate 27 (03 Sep 2021)](#release-candidate-27-03-sep-2021)
 - [Release Candidate 26 (20 Jul 2021)](#release-candidate-26-20-jul-2021)
@@ -28,6 +29,15 @@
 - [Release Candidate 2 (29 Sep 2019)](#release-candidate-2-29-sep-2019)
 - [Release Candidate 1 (26 Sep 2019)](#release-candidate-1-26-sep-2019)
 
+## Release Candidate 29 (TBD)
+
+#### Additions
+
+#### Changes
+
+#### Fixes
+* Fixed #3218
+
 ## Release Candidate 28 (06 Sep 2021)
 
 #### Fixes

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/items/blocks/BlockPlacer.java

@@ -107,7 +107,8 @@ public class BlockPlacer extends SlimefunItem {
                     if (!(item instanceof NotPlaceable)) {
                         placeSlimefunBlock(item, e.getItem(), facedBlock, dispenser);
                     }
-                } else {
+                } else if (!Slimefun.getIntegrations().isCustomItem(e.getItem())) {
+                    // Fixes #3218 - Prevent placement of custom items (ItemsAdder)
                     placeBlock(e.getItem(), facedBlock, dispenser);
                 }
             }

src/main/java/io/github/thebusybiscuit/slimefun4/integrations/IntegrationsManager.java

@@ -267,6 +267,28 @@ public class IntegrationsManager {
         return false;
     }
 
+    /**
+     * This checks if one of our third party integrations defines a given
+     * {@link ItemStack} as custom.
+     * 
+     * @param item
+     *            The {@link ItemStack} to check
+     * 
+     * @return Whether this {@link ItemStack} is a custom item
+     */
+    @SuppressWarnings("deprecation")
+    public boolean isCustomItem(@Nonnull ItemStack item) {
+        if (isItemsAdderInstalled) {
+            try {
+                return ItemsAdder.isCustomItem(item);
+            } catch (Exception | LinkageError x) {
+                logError("ItemsAdder", x);
+            }
+        }
+
+        return false;
+    }
+
     /**
      * This method removes any temporary enchantments from the given {@link ItemStack}.
      * Some plugins apply enchantments for a short amount of time and remove it later.