SPIGOT-5751: Clarify behaviour of block drop-related API methods

By: Lars Dormans <lars.dormans@live.nl>

paper-api/src/main/java/org/bukkit/block/Block.java

@@ -376,7 +376,8 @@ public interface Block extends Metadatable {
     PistonMoveReaction getPistonMoveReaction();
 
     /**
-     * Breaks the block and spawns items as if a player had digged it
+     * Breaks the block and spawns items as if a player had digged it regardless
+     * of the tool.
      *
      * @return true if the block was destroyed
      */
@@ -389,7 +390,7 @@ public interface Block extends Metadatable {
      * @param tool The tool or item in hand used for digging
      * @return true if the block was destroyed
      */
-    boolean breakNaturally(@NotNull ItemStack tool);
+    boolean breakNaturally(@Nullable ItemStack tool);
 
     /**
      * Returns a list of items which would drop by destroying this block
@@ -407,7 +408,7 @@ public interface Block extends Metadatable {
      * @return a list of dropped items for this type of block
      */
     @NotNull
-    Collection<ItemStack> getDrops(@NotNull ItemStack tool);
+    Collection<ItemStack> getDrops(@Nullable ItemStack tool);
 
     /**
      * Returns a list of items which would drop by the entity destroying this