#3621: Warn about use of valid chat colors and add test

chat/src/main/java/net/md_5/bungee/api/chat/BaseComponent.java

@@ -253,6 +253,9 @@ public abstract class BaseComponent
 
     /**
      * Set this component's color.
+     * <p>
+     * <b>Warning: This should be a color, not formatting code (ie,
+     * {@link ChatColor#getColor()} should not be null).</b>
      *
      * @param color the component color, or null to use the default
      */

chat/src/main/java/net/md_5/bungee/api/chat/ComponentStyle.java

@@ -18,6 +18,9 @@ public final class ComponentStyle implements Cloneable
 
     /**
      * The color of this style.
+     * <p>
+     * <b>Warning: This should be a color, not formatting code (ie,
+     * {@link ChatColor#getColor()} should not be null).</b>
      */
     private ChatColor color;
     /**