do null checks after assignment so that default==null is covered; only

assign value once so that final fields work (ecj)

test/transform/resource/after-ecj/SuperBuilderWithNonNull.java

@@ -0,0 +1,97 @@
+import java.util.List;
+public class SuperBuilderWithNonNull {
+  public static @lombok.experimental.SuperBuilder class Parent {
+    public static abstract @java.lang.SuppressWarnings("all") class ParentBuilder<C extends Parent, B extends ParentBuilder<C, B>> {
+      private @java.lang.SuppressWarnings("all") String nonNullParentField;
+      private @java.lang.SuppressWarnings("all") boolean nonNullParentField$set;
+      public ParentBuilder() {
+        super();
+      }
+      protected abstract @java.lang.SuppressWarnings("all") B self();
+      public abstract @java.lang.SuppressWarnings("all") C build();
+      public @java.lang.SuppressWarnings("all") B nonNullParentField(final String nonNullParentField) {
+        this.nonNullParentField = nonNullParentField;
+        nonNullParentField$set = true;
+        return self();
+      }
+      public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
+        return (("SuperBuilderWithNonNull.Parent.ParentBuilder(nonNullParentField=" + this.nonNullParentField) + ")");
+      }
+    }
+    private static final @java.lang.SuppressWarnings("all") class ParentBuilderImpl extends ParentBuilder<Parent, ParentBuilderImpl> {
+      private ParentBuilderImpl() {
+        super();
+      }
+      protected @java.lang.Override @java.lang.SuppressWarnings("all") ParentBuilderImpl self() {
+        return this;
+      }
+      public @java.lang.Override @java.lang.SuppressWarnings("all") Parent build() {
+        return new Parent(this);
+      }
+    }
+    final @lombok.NonNull @lombok.Builder.Default String nonNullParentField;
+    private static @java.lang.SuppressWarnings("all") String $default$nonNullParentField() {
+      return "default";
+    }
+    protected @java.lang.SuppressWarnings("all") Parent(final ParentBuilder<?, ?> b) {
+      super();
+      if (b.nonNullParentField$set)
+          this.nonNullParentField = b.nonNullParentField;
+      else
+          this.nonNullParentField = Parent.$default$nonNullParentField();
+      if ((nonNullParentField == null))
+          {
+            throw new java.lang.NullPointerException("nonNullParentField is marked @NonNull but is null");
+          }
+    }
+    public static @java.lang.SuppressWarnings("all") ParentBuilder<?, ?> builder() {
+      return new ParentBuilderImpl();
+    }
+  }
+  public static @lombok.experimental.SuperBuilder class Child extends Parent {
+    public static abstract @java.lang.SuppressWarnings("all") class ChildBuilder<C extends Child, B extends ChildBuilder<C, B>> extends Parent.ParentBuilder<C, B> {
+      private @java.lang.SuppressWarnings("all") String nonNullChildField;
+      public ChildBuilder() {
+        super();
+      }
+      protected abstract @java.lang.Override @java.lang.SuppressWarnings("all") B self();
+      public abstract @java.lang.Override @java.lang.SuppressWarnings("all") C build();
+      public @java.lang.SuppressWarnings("all") B nonNullChildField(final String nonNullChildField) {
+        this.nonNullChildField = nonNullChildField;
+        return self();
+      }
+      public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
+        return (((("SuperBuilderWithNonNull.Child.ChildBuilder(super=" + super.toString()) + ", nonNullChildField=") + this.nonNullChildField) + ")");
+      }
+    }
+    private static final @java.lang.SuppressWarnings("all") class ChildBuilderImpl extends ChildBuilder<Child, ChildBuilderImpl> {
+      private ChildBuilderImpl() {
+        super();
+      }
+      protected @java.lang.Override @java.lang.SuppressWarnings("all") ChildBuilderImpl self() {
+        return this;
+      }
+      public @java.lang.Override @java.lang.SuppressWarnings("all") Child build() {
+        return new Child(this);
+      }
+    }
+    @lombok.NonNull String nonNullChildField;
+    protected @java.lang.SuppressWarnings("all") Child(final ChildBuilder<?, ?> b) {
+      super(b);
+      this.nonNullChildField = b.nonNullChildField;
+      if ((nonNullChildField == null))
+          {
+            throw new java.lang.NullPointerException("nonNullChildField is marked @NonNull but is null");
+          }
+    }
+    public static @java.lang.SuppressWarnings("all") ChildBuilder<?, ?> builder() {
+      return new ChildBuilderImpl();
+    }
+  }
+  public SuperBuilderWithNonNull() {
+    super();
+  }
+  public static void test() {
+    Child x = Child.builder().nonNullChildField("child").nonNullParentField("parent").build();
+  }
+}