@@ -0,0 +1,984 @@
+package com.fasterxml.jackson.databind.ser.jdk;%0A%0Aimport java.util.Collections;%0Aimport java.util.Map;%0A%0Aimport com.fasterxml.jackson.annotation.JsonValue;%0Aimport com.fasterxml.jackson.databind.*;%0A%0Apublic class MapKeySerialization2306Test extends BaseMapTest%0A%7B%0A    static class JsonValue2306Key %7B%0A        @JsonValue%0A        private String id;%0A%0A        public JsonValue2306Key(String id) %7B%0A            this.id = id;%0A        %7D%0A    %7D%0A%0A    /*%0A    /**********************************************************************%0A    /* Test methods%0A    /**********************************************************************%0A     */%0A%0A    private final ObjectMapper MAPPER = newJsonMapper();%0A%0A    public void testMapKeyWithJsonValue() throws Exception%0A    %7B%0A        final Map%3CJsonValue2306Key, String%3E map = Collections.singletonMap(%0A                new JsonValue2306Key(%22myId%22), %22value%22);%0A        assertEquals(aposToQuotes(%22%7B'myId':'value'%7D%22),%0A                MAPPER.writeValueAsString(map));%0A    %7D%0A%7D%0A

Add a test to show that #2306 was already implemented