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

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

You can also browse Jackson Core Source Code below:

⏎ com/fasterxml/jackson/core/util/RequestPayload.java

package com.fasterxml.jackson.core.util;

import java.io.IOException;

/**
 * Container object used to contain optional information on content
 * being parsed, passed to {@link com.fasterxml.jackson.core.JsonParseException} in case of
 * exception being thrown; this may be useful for caller to display
 * information on failure.
 *
 * @since 2.8
 */
public class RequestPayload
    implements java.io.Serializable // just in case, even though likely included as transient
{
    private static final long serialVersionUID = 1L;

    // request payload as byte[]
    protected byte[] _payloadAsBytes;

    // request payload as String
    protected CharSequence _payloadAsText;

    // Charset if the request payload is set in bytes
    protected String _charset;

    public RequestPayload(byte[] bytes, String charset) {
        if (bytes == null) {
            throw new IllegalArgumentException();
        }
        _payloadAsBytes = bytes;
        _charset = (charset == null || charset.isEmpty()) ? "UTF-8" : charset;
    }

    public RequestPayload(CharSequence str) {
        if (str == null) {
            throw new IllegalArgumentException();
        }
        _payloadAsText = str;
    }

    /**
     * Returns the raw request payload object i.e, either byte[] or String
     * 
     * @return Object which is a raw request payload i.e, either byte[] or
     *         String
     */
    public Object getRawPayload() {
        if (_payloadAsBytes != null) {
            return _payloadAsBytes;
        }

        return _payloadAsText;
    }

    @Override
    public String toString() {
        if (_payloadAsBytes != null) {
            try {
                return new String(_payloadAsBytes, _charset);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return _payloadAsText.toString();
    }
}

⏎ com/fasterxml/jackson/core/util/RequestPayload.java

Or download all of them as a single archive file:

File name: jackson-core-2.14.0-sources.jar
File size: 497693 bytes
Release date: 2022-11-05
Download 

⇒ Download and Install Jackson Binary Package

⇐ What Is Jackson

⇑ Downloading and Reviewing jackson-*.jar

⇑⇑ Jackson - Java JSON library