http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.crypto.tls;

public class MaxFragmentLength
{
    /*
     * RFC 3546 3.2.
     */
    public static final short pow2_9 = 1;
    public static final short pow2_10 = 2;
    public static final short pow2_11 = 3;
    public static final short pow2_12 = 4;

    public static boolean isValid(short maxFragmentLength)
    {
        return maxFragmentLength >= pow2_9 && maxFragmentLength <= pow2_12;
    }
}