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

⏎ org/omg/PortableServer/ServantLocator.java

package org.omg.PortableServer;


/**
* org/omg/PortableServer/ServantLocator.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/org/omg/PortableServer/poa.idl
* Saturday, October 6, 2018 9:30:42 AM PDT
*/


/**
	 * When the POA has the NON_RETAIN policy it uses servant 
	 * managers that are ServantLocators. Because the POA 
	 * knows that the servant returned by this servant 
	 * manager will be used only for a single request, 
	 * it can supply extra information to the servant 
	 * manager's operations and the servant manager's pair 
	 * of operations may be able to cooperate to do 
	 * something different than a ServantActivator. 
	 * When the POA uses the ServantLocator interface, 
	 * immediately after performing the operation invocation 
	 * on the servant returned by preinvoke, the POA will 
	 * invoke postinvoke on the servant manager, passing the 
	 * ObjectId value and the Servant value as parameters 
	 * (among others). This feature may be used to force 
	 * every request for objects associated with a POA to 
	 * be mediated by the servant manager.
	 */
public interface ServantLocator extends ServantLocatorOperations, org.omg.PortableServer.ServantManager, org.omg.CORBA.portable.IDLEntity 
{
} // interface ServantLocator

⏎ org/omg/PortableServer/ServantLocator.java

Or download all of them as a single archive file:

File name: jre-rt-org-1.8.0_191-src.zip
File size: 951125 bytes
Release date: 2018-10-28
Download 

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

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

⇑ Download and Use JDK 8

⇑⇑ FAQ for JDK (Java Development Kit)