What Is fop.jar? I got it from the fop-2.7-bin.zip.

fop.jar in fop-2.7-bin.zip is the JAR file for FOP 2.7, which is a print formatter driven by XSL formatting objects (XSL-FO). You can obtain fop.jar from the build folder of the fop-2.7-bin.zip file.

Below is the information about the fop.jar (2.2) file:

JAR File Size and Download Location:

JAR name: fop.jar, fop-2.7.jar
Target JDK version: 1.7
File name: fop.jar
File size: 4442817 bytes
Release date: 20-Jan-2022
Download: Apache FOP Website

Java source code files for fop.jar:

⏎ org/apache/fop/fo/UnknownXMLObj.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* $Id: UnknownXMLObj.java 680378 2008-07-28 15:05:14Z jeremias $ */

package org.apache.fop.fo;

import org.xml.sax.Locator;

import org.apache.fop.apps.FOPException;

/**
 * Class for handling generic XML from a namespace not recognized by FOP
 */
public class UnknownXMLObj extends XMLObj {
    private String namespace;

    /**
     * Inner class for an UnknownXMLObj Maker
     */
    public static class Maker extends ElementMapping.Maker {
        private String space;

        /**
         * Construct the Maker
         * @param ns the namespace for this Maker
         */
        public Maker(String ns) {
            space = ns;
        }

        /**
         * Make an instance
         * @param parent FONode that is the parent of the object
         * @return the created UnknownXMLObj
         */
        public FONode make(FONode parent) {
            return new UnknownXMLObj(parent, space);
        }
    }

    /**
     * Constructs an unknown xml object (called by Maker).
     *
     * @param parent the parent formatting object
     * @param space the namespace for this object
     */
    protected UnknownXMLObj(FONode parent, String space) {
        super(parent);
        this.namespace = space;
    }

    /** {@inheritDoc} */
    public String getNamespaceURI() {
        return this.namespace;
    }

    /** {@inheritDoc} */
    public String getNormalNamespacePrefix() {
        return null; //We don't know that in this case.
    }

    /** {@inheritDoc} */
    protected void addChildNode(FONode child) {
        if (doc == null) {
            createBasicDocument();
        }
        super.addChildNode(child);
    }

    /** {@inheritDoc} */
    protected void characters(char[] data, int start, int length,
                                 PropertyList pList, Locator locator) throws FOPException {
        if (doc == null) {
            createBasicDocument();
        }
        super.characters(data, start, length, pList, locator);
    }

}

⏎ org/apache/fop/fo/UnknownXMLObj.java

Or download all of them as a single archive file:

File name: fop-2.7-src.zip
File size: 3401312 bytes
Release date: 2022-01-20
Download 

⇒ "fop" Command in fop-2.7-bin.zip

⇐ What Is fop-2.7-bin.zip

⇑ Download and Installing of FOP 2.x

⇑⇑ FAQ for FOP (Formatting Object Processor)