[fixes #2120] ecj was not generating explicit nullchecks for builder-setters.

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

@@ -0,0 +1,34 @@
+@lombok.Builder class BuilderWithNonNull {
+  public static @java.lang.SuppressWarnings("all") class BuilderWithNonNullBuilder {
+    private @java.lang.SuppressWarnings("all") String id;
+    @java.lang.SuppressWarnings("all") BuilderWithNonNullBuilder() {
+      super();
+    }
+    public @java.lang.SuppressWarnings("all") BuilderWithNonNullBuilder id(final @lombok.NonNull String id) {
+      if ((id == null))
+          {
+            throw new java.lang.NullPointerException("id is marked non-null but is null");
+          }
+      this.id = id;
+      return this;
+    }
+    public @java.lang.SuppressWarnings("all") BuilderWithNonNull build() {
+      return new BuilderWithNonNull(id);
+    }
+    public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
+      return (("BuilderWithNonNull.BuilderWithNonNullBuilder(id=" + this.id) + ")");
+    }
+  }
+  private final @lombok.NonNull String id;
+  @java.lang.SuppressWarnings("all") BuilderWithNonNull(final @lombok.NonNull String id) {
+    super();
+    if ((id == null))
+        {
+          throw new java.lang.NullPointerException("id is marked non-null but is null");
+        }
+    this.id = id;
+  }
+  public static @java.lang.SuppressWarnings("all") BuilderWithNonNullBuilder builder() {
+    return new BuilderWithNonNullBuilder();
+  }
+}