Fix upstream javadocs

paper-api/src/main/java/org/bukkit/block/data/BlockData.java

@@ -224,7 +224,7 @@ public interface BlockData extends Cloneable {
      * {@link Material#REDSTONE_WIRE} -> {@link Material#REDSTONE}
      * {@link Material#CARROTS} -> {@link Material#CARROT}
      * </pre>
-     * @return placement material
+     * @return placement material or {@link Material#AIR} if it doesn't have one
      */
     @NotNull
     Material getPlacementMaterial();

paper-api/src/main/java/org/bukkit/block/data/FaceAttachable.java

@@ -38,7 +38,7 @@ public interface FaceAttachable extends BlockData {
          */
         WALL,
         /**
-         * The switch is mounted to the ceiling and pointing dowanrds.
+         * The switch is mounted to the ceiling and pointing downwards.
          */
         CEILING;
     }

paper-api/src/main/java/org/bukkit/block/data/type/CommandBlock.java

@@ -4,7 +4,7 @@ import org.bukkit.block.data.Directional;
 
 /**
  * 'conditional' denotes whether this command block is conditional or not, i.e.
- * will only execute if the preceeding command block also executed successfully.
+ * will only execute if the preceding command block also executed successfully.
  */
 public interface CommandBlock extends Directional {
 

paper-api/src/main/java/org/bukkit/block/data/type/Gate.java

@@ -5,7 +5,7 @@ import org.bukkit.block.data.Openable;
 import org.bukkit.block.data.Powerable;
 
 /**
- * 'in_wall" indicates if the fence gate is attached to a wall, and if true the
+ * 'in_wall' indicates if the fence gate is attached to a wall, and if true the
  * texture is lowered by a small amount to blend in better.
  */
 public interface Gate extends Directional, Openable, Powerable {

paper-api/src/main/java/org/bukkit/block/data/type/Switch.java

@@ -21,7 +21,7 @@ public interface Switch extends Directional, FaceAttachable, Powerable {
      * Sets the value of the 'face' property.
      *
      * @param face the new 'face' value
-     * @deprecated use {@link #getAttachedFace()}
+     * @deprecated use {@link #setAttachedFace(AttachedFace)}
      */
     @Deprecated(since = "1.15.2")
     void setFace(@NotNull Face face);
@@ -42,7 +42,7 @@ public interface Switch extends Directional, FaceAttachable, Powerable {
          */
         WALL,
         /**
-         * The switch is mounted to the ceiling and pointing dowanrds.
+         * The switch is mounted to the ceiling and pointing downwards.
          */
         CEILING;
     }