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/jmx/remote/internal/IIOPProxy.java

/*
 * Copyright (c) 2009, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
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 *
 *
 *
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 *
 */

package com.sun.jmx.remote.internal;

import java.util.Properties;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.NoSuchObjectException;

/**
 * An interface to a subset of the RMI-IIOP and CORBA APIs to avoid a
 * static dependencies on the types defined by these APIs.
 */

public interface IIOPProxy {

    /**
     * Returns true if the given object is a Stub.
     */
    boolean isStub(Object obj);

    /**
     * Returns the Delegate to which the given Stub delegates.
     */
    Object getDelegate(Object stub);

    /**
     * Sets the Delegate for a given Stub.
     */
    void setDelegate(Object stub, Object delegate);

    /**
     * Returns the ORB associated with the given stub
     *
     * @throws  UnsupportedOperationException
     *          if the object does not support the operation that
     *          was invoked
     */
    Object getOrb(Object stub);

    /**
     * Connects the Stub to the given ORB.
     */
    void connect(Object stub, Object orb) throws RemoteException;

    /**
     * Returns true if the given object is an ORB.
     */
    boolean isOrb(Object obj);

    /**
     * Creates, and returns, a new ORB instance.
     */
    Object createOrb(String[] args, Properties props);

    /**
     * Converts a string, produced by the object_to_string method, back
     * to a CORBA object reference.
     */
    Object stringToObject(Object orb, String str);

    /**
     * Converts the given CORBA object reference to a string.
     */
    String objectToString(Object orb, Object obj);

    /**
     * Checks to ensure that an object of a remote or abstract interface
     * type can be cast to a desired type.
     */
    <T> T narrow(Object narrowFrom, Class<T> narrowTo);

    /**
     * Makes a server object ready to receive remote calls
     */
    void exportObject(Remote obj) throws RemoteException;

    /**
     * Deregisters a server object from the runtime.
     */
    void unexportObject(Remote obj) throws NoSuchObjectException;

    /**
     * Returns a stub for the given server object.
     */
    Remote toStub(Remote obj) throws NoSuchObjectException;
}

⏎ com/sun/jmx/remote/internal/IIOPProxy.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 

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