[Adventure hook] Fix startup error when an older version of the libra…

…ry is present

shared/src/main/java/me/neznamy/tab/shared/hook/AdventureHook.java

@@ -8,7 +8,6 @@
 import me.neznamy.tab.shared.util.ReflectionUtils;
 import net.kyori.adventure.key.Key;
 import net.kyori.adventure.text.Component;
-import net.kyori.adventure.text.format.ShadowColor;
 import net.kyori.adventure.text.format.Style;
 import net.kyori.adventure.text.format.TextColor;
 import net.kyori.adventure.text.format.TextDecoration;
@@ -45,8 +44,8 @@ public static Component convert(@NotNull TabComponent component) {
                 .decoration(TextDecoration.STRIKETHROUGH, getDecoration(component.getModifier().getStrikethrough()))
                 .decoration(TextDecoration.OBFUSCATED, getDecoration(component.getModifier().getObfuscated()))
                 .font(component.getModifier().getFont() == null ? null : Key.key(component.getModifier().getFont()));
-        if (SHADOW_COLOR_AVAILABLE && component.getModifier().getShadowColor() != null) {
-            style.shadowColor(ShadowColor.shadowColor(component.getModifier().getShadowColor()));
+        if (SHADOW_COLOR_AVAILABLE) {
+            AdventureShadowHook.setShadowColor(style, component.getModifier().getShadowColor());
         }
 
         // Extra
@@ -99,7 +98,7 @@ public static TabComponent convert(@NotNull Component component) {
         Map<TextDecoration, TextDecoration.State> decorations = component.style().decorations();
         tabComponent.setModifier(new ChatModifier(
                 component.color() == null ? null : new me.neznamy.tab.shared.chat.TextColor(component.color().value()),
-                !SHADOW_COLOR_AVAILABLE || component.shadowColor() == null ? null : component.shadowColor().value(),
+                SHADOW_COLOR_AVAILABLE ? AdventureShadowHook.getShadowColor(component) : null,
                 getDecoration(decorations.get(TextDecoration.BOLD)),
                 getDecoration(decorations.get(TextDecoration.ITALIC)),
                 getDecoration(decorations.get(TextDecoration.UNDERLINED)),

shared/src/main/java/me/neznamy/tab/shared/hook/AdventureShadowHook.java

@@ -0,0 +1,43 @@
+package me.neznamy.tab.shared.hook;
+
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.format.ShadowColor;
+import net.kyori.adventure.text.format.Style;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * A separate class for handling shadow color in adventure components.
+ * It is required to be separate. Using static functions on interfaces causes
+ * it to load on class initialization even if the code never runs, resulting in an error
+ * when using an older version of the library before shadow color class was added.
+ */
+public class AdventureShadowHook {
+
+    /**
+     * Returns shadow color of the component in ARGB format or {@code null} if not defined.
+     *
+     * @param   component
+     *          Component to get shadow color of
+     * @return  Shadow color of the component in ARGB format or {@code null} if not defined
+     */
+    @Nullable
+    public static Integer getShadowColor(@NotNull Component component) {
+        ShadowColor color = component.shadowColor();
+        return color == null ? null : color.value();
+    }
+
+    /**
+     * Sets shadow color for the style in AGB format if it is not {@code null}.
+     *
+     * @param   style
+     *          Style to set shadow color of
+     * @param   shadowColor
+     *          Shadow color in ARGB format or {@code null} for default
+     */
+    public static void setShadowColor(@NotNull Style.Builder style, @Nullable Integer shadowColor) {
+        if (shadowColor != null) {
+            style.shadowColor(ShadowColor.shadowColor(shadowColor));
+        }
+    }
+}