Combination of JsonMerge and JsonManagedReference fails

[miguelocarvajal]

I have an issue where if I use a List with both JsonMerge and JsonManagedReference annotations, the back reference is null.

I came up with the following test case:

Test class

package com.carvajalonline;

import java.util.List;

import com.fasterxml.jackson.databind.ObjectMapper;

public class Test {
	public static void main(String[] args) {
		ObjectMapper objectMapper = new ObjectMapper();

		try {
			Invoice invoice = objectMapper.readValue("{\"lines\": [{\"id\": 20, \"total\": \"$200.00\"}]}", Invoice.class);

			List<InvoiceLine> lines = invoice.getLines();
			for (InvoiceLine invoiceLine : lines) {
				System.out.println("line: " + invoiceLine.getId() + " - " + invoiceLine.getInvoice());
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

Invoice class

package com.carvajalonline;

import java.util.ArrayList;
import java.util.List;

import com.fasterxml.jackson.annotation.JsonManagedReference;
import com.fasterxml.jackson.annotation.JsonMerge;

public class Invoice {
	@JsonManagedReference("invoice")
	@JsonMerge
	private List<InvoiceLine> lines = new ArrayList<>();

	public Invoice() {
		lines.add(new InvoiceLine(10, "$100.00", this));
	}

	public List<InvoiceLine> getLines() {
		return lines;
	}

	public void setLines(List<InvoiceLine> lines) {
		this.lines = lines;
	}
}

InvoiceLine class

package com.carvajalonline;

import com.fasterxml.jackson.annotation.JsonBackReference;

public class InvoiceLine {
	private Integer id;
	private String total;
	@JsonBackReference("invoice")
	private Invoice invoice;

	public InvoiceLine() {
		
	}

	public InvoiceLine(Integer id, String total, Invoice invoice) {
		this.id = id;
		this.total = total;
		this.invoice = invoice;
	}

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getTotal() {
		return total;
	}

	public void setTotal(String total) {
		this.total = total;
	}

	public Invoice getInvoice() {
		return invoice;
	}

	public void setInvoice(Invoice invoice) {
		this.invoice = invoice;
	}
}

I expect the output to be:

line: 10 - com.carvajalonline.Invoice@XXXX line: 20 - com.carvajalonline.Invoice@XXXX

However, when I introduce the JsonMerge annotation, the output I get is: line: 10 - com.carvajalonline.Invoice@XXXX line: 20 - null (SHOULD NOT BE GETTING NULL HERE)

If I remove the JsonMerge annotation, I get this output line: 20 - com.carvajalonline.Invoice@XXXX

Obviously when the JsonMerge annotation is removed, line 10 no longer appears because the array is being replaced, however the invoice is no longer null.

I am using version 2.9.5 to produce this bug. Any pointers as to how this can be handled?

Thanks!