SuperBuilder toBuilder: moved static helper method to builder impl

test/transform/resource/before/SuperBuilderAbstractToBuilder.java

@@ -0,0 +1,20 @@
+public class SuperBuilderAbstractToBuilder {
+	@lombok.experimental.SuperBuilder(toBuilder = true)
+	public static class Parent {
+		int parentField;
+	}
+	
+	@lombok.experimental.SuperBuilder(toBuilder = true)
+	public abstract static class Child extends Parent {
+		double childField;
+	}
+	
+	@lombok.experimental.SuperBuilder(toBuilder = true)
+	public static class GrandChild extends Child {
+		String grandChildField;
+	}
+	
+	public static void test() {
+		GrandChild x = GrandChild.builder().grandChildField("").parentField(5).childField(2.5).build().toBuilder().build();
+	}
+}