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/area/inline/Container.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: Container.java 1562429 2014-01-29 12:52:26Z vhennebert $ */

package org.apache.fop.area.inline;

import java.util.ArrayList;
import java.util.List;

import org.apache.fop.area.Area;
import org.apache.fop.area.Block;

/**
 * Container area for inline container.
 * This area should be placed in a viewport as a result of the
 * inline container formatting object.
 * This allows an inline area to have blocks as children.
 */
public class Container extends Area {

    private static final long serialVersionUID = 5256423939348189260L;

    /**
     * The list of block areas stacked inside this container
     */
    protected List<Block> blocks = new ArrayList<Block>();

    /**
     * The width of this container
     */
    protected int width;

    /**
     * Create a new container area
     */
    public Container() {
    }

    @Override
    public void addChildArea(Area child) {
        if (!(child instanceof Block)) {
            throw new IllegalArgumentException("Container only accepts block areas");
        }
        blocks.add((Block) child);
    }

    /**
     * Get the block areas stacked inside this container area.
     *
     * @return the list of block areas
     */
    public List<Block> getBlocks() {
        return blocks;
    }

    /**
     * Get the width of this container area.
     *
     * @return the width
     */
    public int getWidth() {
        return width;
    }
}

⏎ org/apache/fop/area/inline/Container.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)