Add generic type to NodeBuilder interface

Author: hjohn

fx-builders/src/main/java/org/int4/fx/builders/common/AbstractNodeBuilder.java

@@ -20,7 +20,7 @@
  * @param <N> the type of {@link Node} being built
  * @param <B> the concrete builder type
  */
-public abstract class AbstractNodeBuilder<N extends Node, B extends AbstractNodeBuilder<N, B>> extends AbstractOptionBuilder<N, B> implements NodeBuilder {
+public abstract class AbstractNodeBuilder<N extends Node, B extends AbstractNodeBuilder<N, B>> extends AbstractOptionBuilder<N, B> implements NodeBuilder<N> {
 
   /**
    * Constructs a new instance with the given style classes.

fx-builders/src/main/java/org/int4/fx/builders/common/NodeBuilder.java

@@ -8,6 +8,8 @@
 import javafx.scene.control.Label;
 import javafx.scene.control.Tooltip;
 
+import org.int4.fx.builders.FX;
+
 /**
  * Builder capable of creating a {@link Node}.
  * <p>
@@ -18,8 +20,10 @@
  * In such contexts, callers do not need to invoke {@link #build()} explicitly;
  * the builder will be completed automatically when a {@link Node} is required.
  * This enables fluent composition of builders without manual materialization.
+ *
+ * @param <N> the type of node being build
  */
-public interface NodeBuilder {
+public interface NodeBuilder<N extends Node> {
 
   /**
    * Converts the given object into a {@link Node}.
@@ -41,7 +45,7 @@ public interface NodeBuilder {
   static Node toNode(Object node) {
     return switch(node) {
       case Node n -> n;
-      case NodeBuilder b -> b.build();
+      case NodeBuilder<?> b -> b.build();
       case String s -> new Label(s);
       case null -> throw new IllegalArgumentException("node cannot be null");
       // TODO could also allow Observables to be translated to bound labels :)
@@ -75,5 +79,5 @@ static Node[] toNodes(Object... nodes) {
    *
    * @return a new {@link Node}, never {@code null}
    */
-  Node build();
+  N build();
 }