Fix more javadoc warnings

src/main/java/org/spongepowered/api/data/Keys.java

@@ -2608,7 +2608,6 @@ public final class Keys {
      *
      * <p>Vanishing an {@link Entity} ridden by other entities (see
      * {@link #PASSENGERS} will cause problems.</p>
-     * <p>
      */
     public static final Key<Value<Boolean>> VANISH = Keys.key(ResourceKey.sponge("vanish"), TypeTokens.BOOLEAN_VALUE_TOKEN);
 

src/main/java/org/spongepowered/api/entity/living/player/server/ServerPlayer.java

@@ -233,7 +233,7 @@ public interface ServerPlayer extends Player, Subject {
 
     /**
      * Gets the {@link WorldBorder} for this player, if present. If no border is
-     * set, an empty {@code Optional} is returned.
+     * set, {@link Optional#empty()} is returned.
      *
      * @return The {@code WorldBorder} of this player as an {@code Optional}, if
      *     present

src/main/java/org/spongepowered/api/event/world/ChangeWorldBorderEvent.java

@@ -42,7 +42,7 @@ public interface ChangeWorldBorderEvent extends Event, Cancellable {
     /**
      * Gets the border that was previously used as an {@link Optional}. There 
      * may be no border set for the target (especially, if it is a player), in 
-     * which case, an empty {@code Optional} is returned.
+     * which case, {@link Optional#empty()} is returned.
      *
      * @return The border that was previously in use, if there was one.
      */
@@ -51,7 +51,7 @@ public interface ChangeWorldBorderEvent extends Event, Cancellable {
     /**
      * Gets the border that will be used as an {@link Optional}. For some
      * targets, the border may be unset and therefore they may not always have a
-     * border. It is in these instances that an empty {@code Optional} is
+     * border. It is in these instances that {@link Optional#empty()} is
      * returned.
      *
      * @return The border that will be in use, if there is one.

src/main/java/org/spongepowered/api/item/merchant/TradeOfferGenerator.java

@@ -40,9 +40,8 @@ import java.util.function.BiFunction;
  * randomization based on {@link ItemStackGenerator}s for populating
  * {@link ItemStack}s and finally generating a {@link TradeOffer}.
  * <p>
- * <p>
  * <strong>Can be directly implemented as a lambda as follows:</strong>
- * <p><pre> {@code
+ * </p><pre> {@code
  * final TradeOfferGenerator generator = (merchant, random) -> TradeOffer.builder()
  *   .firstBuyingItem(ItemStack.of(ItemTypes.EMERALD, 64))
  *   .sellingItem(ItemStack.builder()

src/main/java/org/spongepowered/api/network/channel/packet/PacketDispatcher.java

@@ -85,6 +85,7 @@ public interface PacketDispatcher {
      *
      * @param player The player to send the packet to
      * @param packet The packet to send
+     * @return A future which will complete when the operation has finished
      */
     default CompletableFuture<Void> sendTo(final ServerPlayer player, final Packet packet) {
         return this.sendTo(player.connection(), packet);
@@ -103,6 +104,7 @@ public interface PacketDispatcher {
      * belongs to.</p>
      *
      * @param packet The packet to send
+     * @return A future which will complete when the operation has finished
      * @throws IllegalStateException If the server connection isn't in the play phase
      */
     default CompletableFuture<Void> sendToServer(final Packet packet) {
@@ -121,6 +123,7 @@ public interface PacketDispatcher {
      *
      * @param connection The connection to send the packet to
      * @param packet The packet to send
+     * @return A future which will complete when the operation has finished
      */
     CompletableFuture<Void> sendTo(EngineConnection connection, Packet packet);
 }

src/main/java/org/spongepowered/api/network/channel/raw/play/RawPlayDataChannel.java

@@ -143,6 +143,7 @@ public interface RawPlayDataChannel {
      *
      * @param player The player to send the message to
      * @param payload A consumer to write the data to
+     * @return A future which will complete when the operation has finished
      */
     default CompletableFuture<Void> sendTo(final ServerPlayer player, final Consumer<ChannelBuf> payload) {
         return this.sendTo(player.connection(), payload);
@@ -154,6 +155,7 @@ public interface RawPlayDataChannel {
      * from the client side.
      *
      * @param payload A consumer to write the data to
+     * @return A future which will complete when the operation has finished
      */
     default CompletableFuture<Void> sendToServer(final Consumer<ChannelBuf> payload) {
         final EngineConnection connection = Sponge.client().connection()
@@ -167,6 +169,7 @@ public interface RawPlayDataChannel {
      *
      * @param connection The client connection to send the message to
      * @param payload A consumer to write the data to
+     * @return A future which will complete when the operation has finished
      */
     CompletableFuture<Void> sendTo(EngineConnection connection, Consumer<ChannelBuf> payload);
 }

src/main/java/org/spongepowered/api/util/blockray/RayTrace.java

@@ -227,7 +227,7 @@ public interface RayTrace<T extends Locatable> {
      *
      * <pre> {@code
      * block -> {
-     *   final BlockType type = block.getBlockState().getType();
+     *   final BlockType type = block.blockState().type();
      *   return type == BlockTypes.AIR.get() ||
      *          type == BlockTypes.CAVE_AIR.get() ||
      *          type == BlockTypes.VOID_AIR.get();
@@ -267,7 +267,7 @@ public interface RayTrace<T extends Locatable> {
      *
      * <pre> {@code
      * block -> {
-     *   final BlockType type = block.getBlockState().getType();
+     *   final BlockType type = block.blockState().type();
      *   return !(type == BlockTypes.AIR.get() &&
      *          type == BlockTypes.CAVE_AIR.get() &&
      *          type == BlockTypes.VOID_AIR.get());