Add some missing deprecation annotations

By: md_5 <git@md-5.net>

paper-api/src/main/java/org/bukkit/NamespacedKey.java

@@ -161,6 +161,7 @@ public final class NamespacedKey {
      */
     @ApiStatus.Internal
     @NotNull
+    @Deprecated
     public static NamespacedKey randomKey() {
         return new NamespacedKey(BUKKIT, UUID.randomUUID().toString());
     }

paper-api/src/main/java/org/bukkit/entity/LingeringPotion.java

@@ -5,4 +5,5 @@ package org.bukkit.entity;
  *
  * @deprecated lingering status depends on only on the potion item.
  */
+@Deprecated
 public interface LingeringPotion extends ThrownPotion { }

paper-api/src/main/java/org/bukkit/event/enchantment/PrepareItemEnchantEvent.java

@@ -69,6 +69,7 @@ public class PrepareItemEnchantEvent extends InventoryEvent implements Cancellab
      * @deprecated Use {@link #getOffers()} instead of this method
      */
     @NotNull
+    @Deprecated
     public int[] getExpLevelCostsOffered() {
         int[] levelOffers = new int[offers.length];
         for (int i = 0; i < offers.length; i++) {

paper-api/src/main/java/org/bukkit/inventory/ItemStack.java

@@ -67,6 +67,7 @@ public class ItemStack implements Cloneable, ConfigurationSerializable, Translat
      * @param damage durability / damage
      * @deprecated see {@link #setDurability(short)}
      */
+    @Deprecated
     public ItemStack(@NotNull final Material type, final int amount, final short damage) {
         this(type, amount, damage, null);
     }

paper-api/src/main/java/org/bukkit/map/MapCanvas.java

@@ -86,6 +86,7 @@ public interface MapCanvas {
      * @param color The color. See {@link MapPalette}.
      * @deprecated Magic value, use {@link #setPixelColor(int, int, Color)}
      */
+    @Deprecated
     public void setPixel(int x, int y, byte color);
 
     /**

paper-api/src/main/java/org/bukkit/material/Step.java

@@ -79,6 +79,7 @@ public class Step extends TexturedMaterial {
      * @deprecated Magic value
      */
     @Override
+    @Deprecated
     protected int getTextureIndex() {
         return getData() & 0x7;
     }

paper-api/src/main/java/org/bukkit/scoreboard/Scoreboard.java

@@ -39,6 +39,7 @@ public interface Scoreboard {
      *     exists
      * @deprecated use {@link #registerNewObjective(String, Criteria, String)}
      */
+    @Deprecated
     @NotNull
     Objective registerNewObjective(@NotNull String name, @NotNull String criteria, @NotNull String displayName);
 
@@ -56,6 +57,7 @@ public interface Scoreboard {
      *     exists
      * @deprecated use {@link #registerNewObjective(String, Criteria, String, RenderType)}
      */
+    @Deprecated
     @NotNull
     Objective registerNewObjective(@NotNull String name, @NotNull String criteria, @NotNull String displayName, @NotNull RenderType renderType);