JRE 8 rt.jar is the JAR file for JRE 8 RT (Runtime) libraries. JRE (Java Runtime) 8 is the runtime environment included in JDK 8. JRE 8 rt.jar libraries are divided into 6 packages:

com.* - Internal Oracle and Sun Microsystems libraries
java.* - Standard Java API libraries.
javax.* - Extended Java API libraries.
jdk.* -  JDK supporting libraries.
org.* - Third party libraries.
sun.* - Old libraries developed by Sun Microsystems.

JAR File Information:

Directory of C:\fyicenter\jdk-1.8.0_191\jre\lib
      63,596,151 rt.jar

Here is the list of Java classes of the com.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ com/sun/corba/se/impl/naming/namingutil/INSURLBase.java

/*
 * Copyright (c) 2002, 2003, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package com.sun.corba.se.impl.naming.namingutil;

/** The corbaloc: URL definitions from the -ORBInitDef and -ORBDefaultInitDef's
 *  will be stored in this object. This object is capable of storing multiple
 *  Host profiles as defined in the CorbaLoc grammer.
 *
 *  @author  Hemanth
 */
public abstract class INSURLBase implements INSURL {

    // If rirFlag is set to true that means internal
    // boot strapping technique will be used. If set to
    // false then the EndpointInfo will be used to create the
    // Service Object reference.
    protected boolean rirFlag = false ;
    protected java.util.ArrayList theEndpointInfo = null ;
    protected String theKeyString = "NameService" ;
    protected String theStringifiedName = null ;

    public boolean getRIRFlag( ) {
        return rirFlag;
    }

    public java.util.List getEndpointInfo( ) {
        return theEndpointInfo;
    }

    public String getKeyString( ) {
        return theKeyString;
    }

    public String getStringifiedName( ) {
        return theStringifiedName;
    }

    public abstract boolean isCorbanameURL( );

    public void dPrint( ) {
        System.out.println( "URL Dump..." );
        System.out.println( "Key String = " + getKeyString( ) );
        System.out.println( "RIR Flag = " + getRIRFlag( ) );
        System.out.println( "isCorbanameURL = " + isCorbanameURL() );
        for( int i = 0; i < theEndpointInfo.size( ); i++ ) {
            ((IIOPEndpointInfo) theEndpointInfo.get( i )).dump( );
        }
        if( isCorbanameURL( ) ) {
            System.out.println( "Stringified Name = " + getStringifiedName() );
        }
    }

}

⏎ com/sun/corba/se/impl/naming/namingutil/INSURLBase.java

Or download all of them as a single archive file:

File name: jre-rt-com-1.8.0_191-src.zip
File size: 8099783 bytes
Release date: 2018-10-28
Download 

⇒ Backup JDK 8 Installation Directory

⇐ JRE 8 rt.jar - org.* Package Source Code

⇑ Download and Use JDK 8

⇑⇑ FAQ for JDK (Java Development Kit)