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/ior/iiop/MaxStreamFormatVersionComponent.java

/*
 * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package com.sun.corba.se.spi.ior.iiop;

import com.sun.corba.se.spi.ior.TaggedComponent ;

// Java to IDL ptc 02-01-12 1.4.11
// TAG_RMI_CUSTOM_MAX_STREAM_FORMAT
public interface MaxStreamFormatVersionComponent extends TaggedComponent
{
    public byte getMaxStreamFormatVersion() ;
}

⏎ com/sun/corba/se/spi/ior/iiop/MaxStreamFormatVersionComponent.java

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