Apache BCEL Source Code Files are inside the Apache BCEL source package file like bcel-6.5.0-src.zip. Unzip the source package file and go to the "src/main" sub-directory, you will see source code files.

Here is the list of Java source code files of the Apache BCEL 6.5.0 in \Users\fyicenter\bcel-6.5.0\src:

⏎ org/apache/bcel/verifier/exc/VerificationException.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.
 *
 */
package org.apache.bcel.verifier.exc;


/**
 * Instances of this class are thrown by BCEL's class file verifier "JustIce" when a
 * class file to verify does not pass one of the verification passes 2 or 3.
 * Note that the pass 3 used by "JustIce" involves verification that is usually
 * delayed to pass 4.
 * The name of this class is justified by the Java Virtual Machine Specification, 2nd
 * edition, page 164, 5.4.1 where verification as a part of the linking process is
 * defined to be the verification happening in passes 2 and 3.
 *
 */
public abstract class VerificationException extends VerifierConstraintViolatedException{
    private static final long serialVersionUID = 8012776320318623652L;

    /**
     * Constructs a new VerificationException with null as its error message string.
     */
    VerificationException() {
        super();
    }
    /**
     * Constructs a new VerificationException with the specified error message.
     */
    VerificationException(final String message) {
        super(message);
    }

    /**
     * Constructs a new VerificationException with the specified error message and exception
     */
    VerificationException(final String message, final Throwable initCause) {
        super(message, initCause);
    }
}

⏎ org/apache/bcel/verifier/exc/VerificationException.java

Or download all of them as a single archive file:

File name: bcel-6.5.0-fyi.zip
File size: 706792 bytes
Release date: 2020-07-03
Download 

⇒ JDK "javap" Command

⇐ Install Apache BCEL 6.5.0 Binary Package

⇑ Apache BCEL (Byte Code Engineering Library)

⇑⇑ Java Bytecode Tools