Как объединить два компаратора?

    public static final Comparator<Flat> COMPARE_BY_NAME = new Comparator<Flat>() {
        @Override
        public int compare(Flat o1, Flat o2) {
            int nameDiff = o1.getName().compareTo(o2.getName());
        return nameDiff;
        }
 
    public static final Comparator<Flat> COMPARE_BY_FLAT_SQUARE = new Comparator<Flat>() {
        @Override
        public int compare(Flat o1, Flat o2) {
            return o1.getFlatSquare() - o2.getFlatSquare();
        }
    };

Flat1, 81
Flat2, 82
Flat1, 83
было бы, например, в возрастающем порядке так:
Flat1, 81
Flat1, 83
Flat2, 82

For example, to sort a collection of String based on the [B]length[/B] and then [B]case-insensitive [/B]natural ordering, the comparator can be composed using following code, 
     Comparator<String> cmp = Comparator.comparingInt(String::length)
             .thenComparing(String.CASE_INSENSITIVE_ORDER);

Comparator<Flat> COMPARE_BY_TWO_FIELDS = Comparator.comparingInt(String::length)
.thenComparing(String.CASE_INSENSITIVE_ORDER);

Comparator<Flat> COMPARE_BY_TWO_FIELDS = COMPARE_BY_NAME.thenComparing(COMPARE_BY_FLAT_SQUARE);

Comparator<Flat> COMPARE_BY_TWO_FIELDS = COMPARE_BY_FLAT_SQUARE.thenComparing(COMPARE_BY_NAME);

    public static final Comparator<Flat> COMPARE_BY_NAME = new Comparator<Flat>() {
        @Override
        public float compare(Flat o1, Flat o2) {
            float nameDiff = o1.getName().compareTo(o2.getName());
        return nameDiff;
        } // Square has Float type
 
    public static final Comparator<Flat> COMPARE_BY_FLAT_SQUARE = new Comparator<Flat>() {
        @Override
        public int compare(Flat o1, Flat o2) {
            return o1.getFlatSquare() - o2.getFlatSquare();
        }
    };

        Comparator<Flat> COMPARE_BY_NAME = new Comparator<Flat>() {
            @Override
            public int compare(Flat o1, Flat o2) {
                int nameDiff = o1.getName().compareTo(o2.getName());
            return nameDiff;
            };
        };
        
        Comparator<Flat> COMPARE_BY_FLAT_SQUARE = new Comparator<Flat>() {
            @Override
            public int compare(Flat o1, Flat o2) {
                return o1.getFlatSquare() - o2.getFlatSquare();
            }; 
        };
        Comparator<Flat> COMPARE_BY_TWO_FIELDS = COMPARE_BY_FLAT_SQUARE.thenComparing(COMPARE_BY_NAME);