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 javax.* package in JRE 1.8.0_191 rt.jar. Java source codes are also provided.

⏎ javax/management/remote/rmi/RMIServer.java

/*
 * Copyright (c) 2002, 2007, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package javax.management.remote.rmi;

import java.io.IOException;
import java.rmi.Remote;
import java.rmi.RemoteException;

/**
 * <p>RMI object used to establish connections to an RMI connector.
 * There is one Remote object implementing this interface for each RMI
 * connector.</p>
 *
 * <p>User code does not usually refer to this interface.  It is
 * specified as part of the public API so that different
 * implementations of that API will interoperate.</p>
 *
 * @since 1.5
 */
public interface RMIServer extends Remote {
    /**
     * <p>The version of the RMI Connector Protocol understood by this
     * connector server.  This is a string with the following format:</p>
     *
     * <pre>
     * <em>protocol-version</em> <em>implementation-name</em>
     * </pre>
     *
     * <p>The <code><em>protocol-version</em></code> is a series of
     * two or more non-negative integers separated by periods
     * (<code>.</code>).  An implementation of the version described
     * by this documentation must use the string <code>1.0</code>
     * here.</p>
     *
     * <p>After the protocol version there must be a space, followed
     * by the implementation name.  The format of the implementation
     * name is unspecified.  It is recommended that it include an
     * implementation version number.  An implementation can use an
     * empty string as its implementation name, for example for
     * security reasons.</p>
     *
     * @return a string with the format described here.
     *
     * @exception RemoteException if there is a communication
     * exception during the remote method call.
     */
    public String getVersion() throws RemoteException;

    /**
     * <p>Makes a new connection through this RMI connector.  Each
     * remote client calls this method to obtain a new RMI object
     * representing its connection.</p>
     *
     * @param credentials this object specifies the user-defined credentials
     * to be passed in to the server in order to authenticate the user before
     * creating the <code>RMIConnection</code>.  Can be null.
     *
     * @return the newly-created connection object.
     *
     * @exception IOException if the new client object cannot be
     * created or exported, or if there is a communication exception
     * during the remote method call.
     *
     * @exception SecurityException if the given credentials do not
     * allow the server to authenticate the caller successfully.
     */
    public RMIConnection newClient(Object credentials) throws IOException;
}

⏎ javax/management/remote/rmi/RMIServer.java

Or download all of them as a single archive file:

File name: jre-rt-javax-1.8.0_191-src.zip
File size: 5381005 bytes
Release date: 2018-10-28
Download 

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

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

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