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

⏎ java/beans/ConstructorProperties.java

/*
 * Copyright (c) 2006, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package java.beans;

import java.lang.annotation.*;
import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;

/**
   <p>An annotation on a constructor that shows how the parameters of
   that constructor correspond to the constructed object's getter
   methods.  For example:

   <blockquote>
<pre>
   public class Point {
       &#64;ConstructorProperties({"x", "y"})
       public Point(int x, int y) {
           this.x = x;
           this.y = y;
       }

       public int getX() {
           return x;
       }

       public int getY() {
           return y;
       }

       private final int x, y;
   }
</pre>
</blockquote>

   The annotation shows that the first parameter of the constructor
   can be retrieved with the {@code getX()} method and the second with
   the {@code getY()} method.  Since parameter names are not in
   general available at runtime, without the annotation there would be
   no way to know whether the parameters correspond to {@code getX()}
   and {@code getY()} or the other way around.

   @since 1.6
*/
@Documented @Target(CONSTRUCTOR) @Retention(RUNTIME)
public @interface ConstructorProperties {
    /**
       <p>The getter names.</p>
       @return the getter names corresponding to the parameters in the
       annotated constructor.
    */
    String[] value();
}

⏎ java/beans/ConstructorProperties.java

Or download all of them as a single archive file:

File name: jre-rt-java-1.8.0_191-src.zip
File size: 6664831 bytes
Release date: 2018-10-28
Download 

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

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