Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Databind Source Code files are provided in the source packge (jackson-databind-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Databind Source Code below:

⏎ com/fasterxml/jackson/databind/KeyDeserializer.java

package com.fasterxml.jackson.databind;

import java.io.IOException;

/**
 * Abstract class that defines API used for deserializing JSON content
 * field names into Java Map keys. These deserializers are only used
 * if the Map key class is not <code>String</code> or <code>Object</code>.
 */
public abstract class KeyDeserializer
{
    /**
     * Method called to deserialize a {@link java.util.Map} key from JSON property name.
     */
    public abstract Object deserializeKey(String key, DeserializationContext ctxt)
        throws IOException;

    /**
     * This marker class is only to be used with annotations, to
     * indicate that <b>no deserializer is configured</b>.
     *<p>
     * Specifically, this class is to be used as the marker for
     * annotation {@link com.fasterxml.jackson.databind.annotation.JsonDeserialize}.
     */
    public abstract static class None
        extends KeyDeserializer { }
}

⏎ com/fasterxml/jackson/databind/KeyDeserializer.java

Or download all of them as a single archive file:

File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
Download 

⇒ Jackson Annotations Source Code

⇐ Download and Install Jackson Binary Package

⇑ Downloading and Reviewing jackson-*.jar

⇑⇑ Jackson - Java JSON library