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/json/JsonWriteFeature.java

package com.fasterxml.jackson.core.json;

import com.fasterxml.jackson.core.*;

/**
 * Token writer features specific to JSON backend.
 *
 * @since 2.10
 */
public enum JsonWriteFeature
    implements FormatFeature
{
    // // // Support for non-standard data format constructs: comments

    // // Quoting/ecsaping-related features
    
    /**
     * Feature that determines whether JSON Object field names are
     * quoted using double-quotes, as specified by JSON specification
     * or not. Ability to disable quoting was added to support use
     * cases where they are not usually expected, which most commonly
     * occurs when used straight from Javascript.
     *<p>
     * Feature is enabled by default (since it is required by JSON specification).
     */
    @SuppressWarnings("deprecation")
    QUOTE_FIELD_NAMES(true, JsonGenerator.Feature.QUOTE_FIELD_NAMES),

    /**
     * Feature that determines whether "NaN" ("not a number", that is, not
     * real number) float/double values are output as JSON strings.
     * The values checked are Double.Nan,
     * Double.POSITIVE_INFINITY and Double.NEGATIVE_INIFINTY (and 
     * associated Float values).
     * If feature is disabled, these numbers are still output using
     * associated literal values, resulting in non-conforming
     * output.
     *<p>
     * Feature is enabled by default.
     */
    @SuppressWarnings("deprecation")
    WRITE_NAN_AS_STRINGS(true, JsonGenerator.Feature.QUOTE_NON_NUMERIC_NUMBERS),

    /**
     * Feature that forces all regular number values to be written as JSON Strings,
     * instead of as JSON Numbers.
     * Default state is 'false', meaning that Java numbers are to
     * be serialized using basic numeric representation but
     * if enabled all such numeric values are instead written out as
     * JSON Strings instead.
     *<p>
     * One use case is to avoid problems with Javascript limitations:
     * since Javascript standard specifies that all number handling
     * should be done using 64-bit IEEE 754 floating point values,
     * result being that some 64-bit integer values can not be
     * accurately represent (as mantissa is only 51 bit wide).
     *<p>
     * Feature is disabled by default.
     */
    @SuppressWarnings("deprecation")
    WRITE_NUMBERS_AS_STRINGS(false, JsonGenerator.Feature.WRITE_NUMBERS_AS_STRINGS),
    
    /**
     * Feature that specifies that all characters beyond 7-bit ASCII
     * range (i.e. code points of 128 and above) need to be output
     * using format-specific escapes (for JSON, backslash escapes),
     * if format uses escaping mechanisms (which is generally true
     * for textual formats but not for binary formats).
     *<p>
     * Feature is disabled by default.
     */
    @SuppressWarnings("deprecation")
    ESCAPE_NON_ASCII(false, JsonGenerator.Feature.ESCAPE_NON_ASCII),

    /**
     * Feature that specifies that hex values are encoded with capital letters.
     *<p>
     * Can be disabled to have a better possibility to compare between other JSON
     * writer libraries, such as JSON.stringify from Javascript.
     *<p>
     * Feature is enabled by default for backwards compatibility with earlier
     * versions.
     *
     * @since 2.14
     */
    @SuppressWarnings("deprecation")
    WRITE_HEX_UPPER_CASE(true, JsonGenerator.Feature.WRITE_HEX_UPPER_CASE),

//23-Nov-2015, tatu: for [core#223], if and when it gets implemented
    /*
     * Feature that specifies handling of UTF-8 content that contains
     * characters beyond BMP (Basic Multilingual Plane), which are
     * represented in UCS-2 (Java internal character encoding) as two
     * "surrogate" characters. If feature is enabled, these surrogate
     * pairs are separately escaped using backslash escapes; if disabled,
     * native output (4-byte UTF-8 sequence, or, with char-backed output
     * targets, writing of surrogates as is which is typically converted
     * by {@link java.io.Writer} into 4-byte UTF-8 sequence eventually)
     * is used.
     *<p>
     * Note that the original JSON specification suggests use of escaping;
     * but that this is not correct from standard UTF-8 handling perspective.
     * Because of two competing goals, this feature was added to allow either
     * behavior to be used, but defaulting to UTF-8 specification compliant
     * mode.
     *<p>
     * Feature is disabled by default.
     */
//    ESCAPE_UTF8_SURROGATES(false, JsonGenerator.Feature.ESCAPE_UTF8_SURROGATES),

    ;

    final private boolean _defaultState;
    final private int _mask;

    /**
     * For backwards compatibility we may need to map to one of existing {@link JsonGenerator.Feature}s;
     * if so, this is the feature to enable/disable.
     */
    final private JsonGenerator.Feature _mappedFeature;
    
    /**
     * Method that calculates bit set (flags) of all features that
     * are enabled by default.
     *
     * @return Bit mask of all features that are enabled by default
     */
    public static int collectDefaults()
    {
        int flags = 0;
        for (JsonWriteFeature f : values()) {
            if (f.enabledByDefault()) {
                flags |= f.getMask();
            }
        }
        return flags;
    }
    
    private JsonWriteFeature(boolean defaultState,
            JsonGenerator.Feature  mapTo) {
        _defaultState = defaultState;
        _mask = (1 << ordinal());
        _mappedFeature = mapTo;
    }

    @Override
    public boolean enabledByDefault() { return _defaultState; }
    @Override
    public int getMask() { return _mask; }
    @Override
    public boolean enabledIn(int flags) { return (flags & _mask) != 0; }

    public JsonGenerator.Feature mappedFeature() { return _mappedFeature; }
}

⏎ com/fasterxml/jackson/core/json/JsonWriteFeature.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