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/classfile/MethodParameters.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.classfile;

import java.io.DataInput;
import java.io.DataOutputStream;
import java.io.IOException;

import org.apache.bcel.Const;

/**
 * This class represents a MethodParameters attribute.
 *
 * @see <a href="https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-4.html#jvms-4.7.24">
 * The class File Format : The MethodParameters Attribute</a>
 * @since 6.0
 */
public class MethodParameters extends Attribute {

    private MethodParameter[] parameters = new MethodParameter[0];

    MethodParameters(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
        super(Const.ATTR_METHOD_PARAMETERS, name_index, length, constant_pool);

        final int parameters_count = input.readUnsignedByte();
        parameters = new MethodParameter[parameters_count];
        for (int i = 0; i < parameters_count; i++) {
            parameters[i] = new MethodParameter(input);
        }
    }

    public MethodParameter[] getParameters() {
        return parameters;
    }

    public void setParameters(final MethodParameter[] parameters) {
        this.parameters = parameters;
    }

    @Override
    public void accept(final Visitor v) {
        v.visitMethodParameters(this);
    }

    @Override
    public Attribute copy(final ConstantPool _constant_pool) {
        final MethodParameters c = (MethodParameters) clone();
        c.parameters = new MethodParameter[parameters.length];

        for (int i = 0; i < parameters.length; i++) {
            c.parameters[i] = parameters[i].copy();
        }
        c.setConstantPool(_constant_pool);
        return c;
    }

    /**
     * Dump method parameters attribute to file stream in binary format.
     *
     * @param file Output file stream
     * @throws IOException
     */
    @Override
       public void dump(final DataOutputStream file) throws IOException {
           super.dump(file);
           file.writeByte(parameters.length);
        for (final MethodParameter parameter : parameters) {
            parameter.dump(file);
        }
    }
}

⏎ org/apache/bcel/classfile/MethodParameters.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