Case insensitive key deserialization for Jackson

CaseInsensitiveKeyDeserializers.java

import org.codehaus.jackson.map.BeanDescription;
import org.codehaus.jackson.map.BeanProperty;
import org.codehaus.jackson.map.DeserializationConfig;
import org.codehaus.jackson.map.DeserializationContext;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.KeyDeserializer;
import org.codehaus.jackson.map.KeyDeserializers;
import org.codehaus.jackson.type.JavaType;

import java.io.IOException;

public class CaseInsensitiveKeyDeserializers
        implements KeyDeserializers
{
    public static final CaseInsensitiveKeyDeserializer DESERIALIZER = new CaseInsensitiveKeyDeserializer();

    @Override
    public KeyDeserializer findKeyDeserializer(JavaType type, DeserializationConfig config, BeanDescription beanDesc, BeanProperty property)
            throws JsonMappingException
    {
        return DESERIALIZER;
    }

    private static class CaseInsensitiveKeyDeserializer
            extends KeyDeserializer
    {
        @Override
        public Object deserializeKey(String key, DeserializationContext ctxt)
                throws IOException
        {
            return key.toLowerCase();
        }
    }
}

TestCaseInsensitiveKeys.java

import org.codehaus.jackson.map.DeserializerProvider;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.deser.StdDeserializerProvider;
import org.testng.annotations.Test;

import java.util.Map;

import static org.testng.Assert.assertEquals;

public class TestCaseInsensitiveKeys
{
    @Test
    public void testObjectMapper()
            throws Exception
    {
        ObjectMapper objectMapper = new ObjectMapper();
        DeserializerProvider provider = new StdDeserializerProvider()
                .withAdditionalKeyDeserializers(new CaseInsensitiveKeyDeserializers());
        objectMapper.setDeserializerProvider(provider);

        Map map = objectMapper.readValue("{\"HELLO\":\"world\"}", Map.class);
        assertEquals(map.get("hello"), "world");
    }
}

seems this method doesn't work with objectMapper.readTree(...