AssertJ.assertThat: Filtering out Map entries in POJO by Key

Question

I'm trying to do an AssertJ assertion filtering out the specific Map entries by their key. The only available method for ignoring - "ignoringFields" doesn't work since the map key is not a field (obviously).

Do you know if there are any way to do such a filtering? Probably custom comparator or anything else.

Here is the code sample for the problem: trying to ignore "Chapter 2" key value comparison.

Note: The real objects I have to compare are auto-generated complex and deep and can have many different maps with the same keys I need to ignore.

import lombok.Data;
import org.junit.jupiter.api.Test;

import java.util.HashMap;
import java.util.Map;

import static org.assertj.core.api.Assertions.assertThat;

public class TestAssertJ {

    @Test
    public void testBook() {
        HashMap<String, Chapter> b1Chapters = new HashMap<String, Chapter>() {{
            put("Chapter 1", new Chapter("text 1"));
            put("Chapter 2", new Chapter("text 2"));
        }};
        Book book = new Book("Harry Potter", b1Chapters);

        HashMap<String, Chapter> b2Chapters = new HashMap<String, Chapter>() {{
            put("Chapter 1", new Chapter("text 1"));
        }};
        Book book2 = new Book("Harry Potter", b2Chapters);

        assertThat(book)
                .usingRecursiveComparison()
                .ignoringFields("Chapter 2")
                .isEqualTo(book2);
    }

    @Data
    class Book {
        private final String title;
        private final Map<String, Chapter> chapters;
    }

    @Data
    class Chapter {
        private final String text;
    }
}