Add tag comments

src/main/java/net/minestom/server/tag/Tag.java

@@ -9,7 +9,14 @@ import java.util.function.BiConsumer;
 import java.util.function.Function;
 import java.util.function.Supplier;
 
-public class Tag<T> {
+/**
+ * Represents a key to retrieve or change a value.
+ * <p>
+ * All tags are serializable.
+ *
+ * @param <T> the tag type
+ */
+public final class Tag<T> {
 
     private final String key;
     private final Function<NBTCompound, T> readFunction;

src/main/java/net/minestom/server/tag/TagHandler.java

@@ -0,0 +1,7 @@
+package net.minestom.server.tag;
+
+/**
+ * Represents an element which can read and write {@link Tag tags}.
+ */
+public interface TagHandler extends TagReader, TagWriter {
+}

src/main/java/net/minestom/server/tag/TagReader.java

@@ -4,11 +4,34 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
+/**
+ * Represents an element which can read {@link Tag tags}.
+ */
 public interface TagReader {
+
+    /**
+     * Reads the specified tag.
+     *
+     * @param tag the tag to read
+     * @param <T> the tag type
+     * @return the read tag, null if not present
+     */
     <T> @Nullable T getTag(@NotNull Tag<T> tag);
 
+    /**
+     * Returns if a tag is present.
+     *
+     * @param tag the tag to check
+     * @return true if the tag is present, false otherwise
+     */
     boolean hasTag(@NotNull Tag<?> tag);
 
+    /**
+     * Converts an nbt compound to a tag reader.
+     *
+     * @param compound the compound to convert
+     * @return a {@link TagReader} capable of reading {@code compound}
+     */
     static @NotNull TagReader fromCompound(@NotNull NBTCompound compound) {
         return new TagReader() {
             @Override

src/main/java/net/minestom/server/tag/TagSerializer.java

@@ -3,9 +3,26 @@ package net.minestom.server.tag;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+/**
+ * Interface used to create custom types compatible with {@link Tag#Custom(String, TagSerializer)}.
+ *
+ * @param <T> the type to serialize
+ */
 public interface TagSerializer<T> {
 
+    /**
+     * Reads the custom tag from a {@link TagReader}.
+     *
+     * @param reader the reader
+     * @return the deserialized value
+     */
     @Nullable T read(@NotNull TagReader reader);
 
+    /**
+     * Writes the custom tag to a {@link TagWriter}.
+     *
+     * @param writer the writer
+     * @param value  the value to serialize
+     */
     void write(@NotNull TagWriter writer, @NotNull T value);
 }

src/main/java/net/minestom/server/tag/TagWriter.java

@@ -4,9 +4,26 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 
+/**
+ * Represents an element which can write {@link Tag tags}.
+ */
 public interface TagWriter {
+
+    /**
+     * Writes the specified type.
+     *
+     * @param tag   the tag to write
+     * @param value the tag value, null to remove
+     * @param <T>   the tag type
+     */
     <T> void setTag(@NotNull Tag<T> tag, @Nullable T value);
 
+    /**
+     * Converts an nbt compound to a tag writer.
+     *
+     * @param compound the compound to convert
+     * @return a {@link TagWriter} capable of writing {@code compound}
+     */
     static @NotNull TagWriter fromCompound(@NotNull NBTCompound compound) {
         return new TagWriter() {
             @Override