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/spi/activation/ServerHelper.java

package com.sun.corba.se.spi.activation;


/**
* com/sun/corba/se/spi/activation/ServerHelper.java .
* Generated by the IDL-to-Java compiler (portable), version "3.2"
* from c:/re/workspace/8-2-build-windows-amd64-cygwin/jdk8u191/11896/corba/src/share/classes/com/sun/corba/se/spi/activation/activation.idl
* Saturday, October 6, 2018 9:30:40 AM PDT
*/


/** Server callback API, passed to Activator in active method.
    */
abstract public class ServerHelper
{
  private static String  _id = "IDL:activation/Server:1.0";

  public static void insert (org.omg.CORBA.Any a, com.sun.corba.se.spi.activation.Server that)
  {
    org.omg.CORBA.portable.OutputStream out = a.create_output_stream ();
    a.type (type ());
    write (out, that);
    a.read_value (out.create_input_stream (), type ());
  }

  public static com.sun.corba.se.spi.activation.Server extract (org.omg.CORBA.Any a)
  {
    return read (a.create_input_stream ());
  }

  private static org.omg.CORBA.TypeCode __typeCode = null;
  synchronized public static org.omg.CORBA.TypeCode type ()
  {
    if (__typeCode == null)
    {
      __typeCode = org.omg.CORBA.ORB.init ().create_interface_tc (com.sun.corba.se.spi.activation.ServerHelper.id (), "Server");
    }
    return __typeCode;
  }

  public static String id ()
  {
    return _id;
  }

  public static com.sun.corba.se.spi.activation.Server read (org.omg.CORBA.portable.InputStream istream)
  {
    return narrow (istream.read_Object (_ServerStub.class));
  }

  public static void write (org.omg.CORBA.portable.OutputStream ostream, com.sun.corba.se.spi.activation.Server value)
  {
    ostream.write_Object ((org.omg.CORBA.Object) value);
  }

  public static com.sun.corba.se.spi.activation.Server narrow (org.omg.CORBA.Object obj)
  {
    if (obj == null)
      return null;
    else if (obj instanceof com.sun.corba.se.spi.activation.Server)
      return (com.sun.corba.se.spi.activation.Server)obj;
    else if (!obj._is_a (id ()))
      throw new org.omg.CORBA.BAD_PARAM ();
    else
    {
      org.omg.CORBA.portable.Delegate delegate = ((org.omg.CORBA.portable.ObjectImpl)obj)._get_delegate ();
      com.sun.corba.se.spi.activation._ServerStub stub = new com.sun.corba.se.spi.activation._ServerStub ();
      stub._set_delegate(delegate);
      return stub;
    }
  }

  public static com.sun.corba.se.spi.activation.Server unchecked_narrow (org.omg.CORBA.Object obj)
  {
    if (obj == null)
      return null;
    else if (obj instanceof com.sun.corba.se.spi.activation.Server)
      return (com.sun.corba.se.spi.activation.Server)obj;
    else
    {
      org.omg.CORBA.portable.Delegate delegate = ((org.omg.CORBA.portable.ObjectImpl)obj)._get_delegate ();
      com.sun.corba.se.spi.activation._ServerStub stub = new com.sun.corba.se.spi.activation._ServerStub ();
      stub._set_delegate(delegate);
      return stub;
    }
  }

}

⏎ com/sun/corba/se/spi/activation/ServerHelper.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)