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/JacksonFeature.java

package com.fasterxml.jackson.core.util;

/**
 * Basic API implemented by Enums used for simple Jackson "features": on/off
 * settings and capabilities exposed as something that can be internally
 * represented as bit sets.
 * Designed to be used with {@link JacksonFeatureSet}.
 *
 * @since 2.12
 */
public interface JacksonFeature
{
    /**
     * Accessor for checking whether this feature is enabled by default.
     *
     * @return Whether this instance is enabled by default or not
     */
    public boolean enabledByDefault();

    /**
     * Returns bit mask for this feature instance; must be a single bit,
     * that is of form {@code 1 << N}.
     *
     * @return Bit mask of this feature
     */
    public int getMask();

    /**
     * Convenience method for checking whether feature is enabled in given bitmask.
     *
     * @param flags Bit field that contains a set of enabled features of this type
     *
     * @return True if this feature is enabled in passed bit field
     */
    public boolean enabledIn(int flags);
}

⏎ com/fasterxml/jackson/core/util/JacksonFeature.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