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. 
public class org.bouncycastle.math.ec.rfc7748.X25519$Friend
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.bouncycastle.math.ec.rfc7748.X25519$Friend
  super_class: java.lang.Object
{
  private static final org.bouncycastle.math.ec.rfc7748.X25519$Friend INSTANCE;
    descriptor: Lorg/bouncycastle/math/ec/rfc7748/X25519$Friend;
    flags: (0x001a) ACC_PRIVATE, ACC_STATIC, ACC_FINAL

  static void <clinit>();
    descriptor: ()V
    flags: (0x0008) ACC_STATIC
    Code:
      stack=2, locals=0, args_size=0
         0: .line 12
            new org.bouncycastle.math.ec.rfc7748.X25519$Friend
            dup
            invokespecial org.bouncycastle.math.ec.rfc7748.X25519$Friend.<init>:()V
            putstatic org.bouncycastle.math.ec.rfc7748.X25519$Friend.INSTANCE:Lorg/bouncycastle/math/ec/rfc7748/X25519$Friend;
            return
      LocalVariableTable:
        Start  End  Slot  Name  Signature

  private void <init>();
    descriptor: ()V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.bouncycastle.math.ec.rfc7748.X25519$Friend this
         0: .line 13
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // org.bouncycastle.math.ec.rfc7748.X25519$Friend this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/bouncycastle/math/ec/rfc7748/X25519$Friend;
}
SourceFile: "X25519.java"
NestHost: org.bouncycastle.math.ec.rfc7748.X25519
InnerClasses:
  public Friend = org.bouncycastle.math.ec.rfc7748.X25519$Friend of org.bouncycastle.math.ec.rfc7748.X25519