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/PropertyMetadata.java

package com.fasterxml.jackson.databind;

import com.fasterxml.jackson.annotation.Nulls;
import com.fasterxml.jackson.databind.introspect.AnnotatedMember;

/**
 * Simple container class used for storing "additional" metadata about
 * properties. Carved out to reduce number of distinct properties that
 * actual property implementations and place holders need to store;
 * since instances are immutable, they can be freely shared.
 * 
 * @since 2.3
 */
public class PropertyMetadata
    implements java.io.Serializable
{
    private static final long serialVersionUID = -1;

    public final static PropertyMetadata STD_REQUIRED = new PropertyMetadata(Boolean.TRUE,
            null, null, null, null, null, null);

    public final static PropertyMetadata STD_OPTIONAL = new PropertyMetadata(Boolean.FALSE,
            null, null, null, null, null, null);

    public final static PropertyMetadata STD_REQUIRED_OR_OPTIONAL = new PropertyMetadata(null,
            null, null, null, null, null, null);

    /**
     * Helper class used for containing information about expected merge
     * information for this property, if merging is expected.
     *
     * @since 2.9
     */
    public final static class MergeInfo
    // NOTE: need not be Serializable, not persisted
    {
        public final AnnotatedMember getter;

        /**
         * Flag that is set if the information came from global defaults,
         * and not from explicit per-property annotations or per-type
         * config overrides.
         */
        public final boolean fromDefaults;

        protected MergeInfo(AnnotatedMember getter, boolean fromDefaults) {
            this.getter = getter;
            this.fromDefaults = fromDefaults;
        }

        public static MergeInfo createForDefaults(AnnotatedMember getter) {
            return new MergeInfo(getter, true);
        }

        public static MergeInfo createForTypeOverride(AnnotatedMember getter) {
            return new MergeInfo(getter, false);
        }

        public static MergeInfo createForPropertyOverride(AnnotatedMember getter) {
            return new MergeInfo(getter, false);
        }
    }

    /**
     * Three states: required, not required and unknown; unknown represented
     * as null.
     */
    protected final Boolean _required;

    /**
     * Optional human-readable description associated with the property.
     */
    protected final String _description;

    /**
     * Optional index of the property within containing Object.
     * 
     * @since 2.4
     */
    protected final Integer _index;

    /**
     * Optional default value, as String, for property; not used for
     * any functionality by core databind, offered as metadata for
     * extensions.
     */
    protected final String _defaultValue;

    /**
     * Settings regarding merging, if property is determined to possibly
     * be mergeable (possibly since global settings may be omitted for
     * non-mergeable types).
     *<p>
     * NOTE: transient since it is assumed that this information is only
     * relevant during initial setup and not needed after full initialization.
     * May be changed if this proves necessary.
     * 
     * @since 2.9
     */
    protected final transient MergeInfo _mergeInfo;

    /**
     * Settings regarding handling of incoming `null`s, both for value itself
     * and, for structured types, content values (array/Collection elements,
     * Map values).
     * 
     * @since 2.9
     */
    protected Nulls _valueNulls, _contentNulls;

    /*
    /**********************************************************
    /* Construction, configuration
    /**********************************************************
     */

    /**
     * @since 2.9
     */
    protected PropertyMetadata(Boolean req, String desc, Integer index, String def,
            MergeInfo mergeInfo, Nulls valueNulls, Nulls contentNulls)
    {
        _required = req;
        _description = desc;
        _index = index;
        _defaultValue = (def == null || def.isEmpty()) ? null : def;
        _mergeInfo = mergeInfo;
        _valueNulls = valueNulls;
        _contentNulls = contentNulls;
    }

    /**
     * @since 2.8.8
     */
    public static PropertyMetadata construct(Boolean req, String desc, Integer index,
            String defaultValue) {
        if ((desc != null) || (index != null) || (defaultValue != null)) {
            return new PropertyMetadata(req, desc, index, defaultValue,
                    null, null, null);
        }
        if (req == null) {
            return STD_REQUIRED_OR_OPTIONAL;
        }
        return req ? STD_REQUIRED : STD_OPTIONAL;
    }

    @Deprecated // since 2.8.8
    public static PropertyMetadata construct(boolean req, String desc, Integer index,
            String defaultValue) {
        if (desc != null || index != null || defaultValue != null) {
            return new PropertyMetadata(req, desc, index, defaultValue,
                    null, null, null);
        }
        return req ? STD_REQUIRED : STD_OPTIONAL;
    }

    /**
     * Minor optimization: let's canonicalize back to placeholders in cases
     * where there is no real data to consider
     */
    protected Object readResolve()
    {
        if ((_description == null) && (_index == null) && (_defaultValue == null)
                && (_mergeInfo == null)
                && (_valueNulls == null) && (_contentNulls == null)) {
            if (_required == null) {
                return STD_REQUIRED_OR_OPTIONAL;
            }
            return _required.booleanValue() ? STD_REQUIRED : STD_OPTIONAL;
        }
        return this;
    }

    public PropertyMetadata withDescription(String desc) {
        return new PropertyMetadata(_required, desc, _index, _defaultValue,
                _mergeInfo, _valueNulls, _contentNulls);
    }

    /**
     * @since 2.9
     */
    public PropertyMetadata withMergeInfo(MergeInfo mergeInfo) {
        return new PropertyMetadata(_required, _description, _index, _defaultValue,
                mergeInfo, _valueNulls, _contentNulls);
    }

    /**
     * @since 2.9
     */
    public PropertyMetadata withNulls(Nulls valueNulls,
            Nulls contentNulls) {
        return new PropertyMetadata(_required, _description, _index, _defaultValue,
                _mergeInfo, valueNulls, contentNulls);
    }

    public PropertyMetadata withDefaultValue(String def) {
        if ((def == null) || def.isEmpty()) {
            if (_defaultValue == null) {
                return this;
            }
            def = null;
        } else if (def.equals(_defaultValue)) {
            return this;
        }
        return new PropertyMetadata(_required, _description, _index, def,
                _mergeInfo, _valueNulls, _contentNulls);
    }
    
    public PropertyMetadata withIndex(Integer index) {
        return new PropertyMetadata(_required, _description, index, _defaultValue,
                _mergeInfo, _valueNulls, _contentNulls);
    }
    
    public PropertyMetadata withRequired(Boolean b) {
        if (b == null) {
            if (_required == null) {
                return this;
            }
        } else if (b.equals(_required)) {
            return this;
        }
        return new PropertyMetadata(b, _description, _index, _defaultValue,
                _mergeInfo, _valueNulls, _contentNulls);
    }

    /*
    /**********************************************************
    /* Accessors
    /**********************************************************
     */

    public String getDescription() { return _description; }

    /**
     * @since 2.5
     */
    public String getDefaultValue() { return _defaultValue; }

    /**
     * Accessor for determining whether property has declared "default value",
     * which may be used by extension modules.
     *
     * @since 2.6
     */
    public boolean hasDefaultValue() { return (_defaultValue != null); }

    public boolean isRequired() { return (_required != null) && _required.booleanValue(); }

    public Boolean getRequired() { return _required; }

    /**
     * @since 2.4
     */
    public Integer getIndex() { return _index; }

    /**
     * @since 2.4
     */
    public boolean hasIndex() { return _index != null; }

    /**
     * @since 2.9
     */
    public MergeInfo getMergeInfo() { return _mergeInfo; }

    /**
     * @since 2.9
     */
    public Nulls getValueNulls() { return _valueNulls; }

    /**
     * @since 2.9
     */
    public Nulls getContentNulls() { return _contentNulls; }
}

⏎ com/fasterxml/jackson/databind/PropertyMetadata.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
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