https://github.com/google/guava/guava: Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. 
class com.google.common.hash.Hashing$Sha256Holder
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.google.common.hash.Hashing$Sha256Holder
  super_class: java.lang.Object
{
  static final com.google.common.hash.HashFunction SHA_256;
    descriptor: Lcom/google/common/hash/HashFunction;
    flags: (0x0018) ACC_STATIC, ACC_FINAL

  static void <clinit>();
    descriptor: ()V
    flags: (0x0008) ACC_STATIC
    Code:
      stack=4, locals=0, args_size=0
         0: .line 205
            new com.google.common.hash.MessageDigestHashFunction
            dup
            ldc "SHA-256"
            ldc "Hashing.sha256()"
            invokespecial com.google.common.hash.MessageDigestHashFunction.<init>:(Ljava/lang/String;Ljava/lang/String;)V
         1: .line 204
            putstatic com.google.common.hash.Hashing$Sha256Holder.SHA_256:Lcom/google/common/hash/HashFunction;
         2: .line 205
            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 // com.google.common.hash.Hashing$Sha256Holder this
         0: .line 203
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // com.google.common.hash.Hashing$Sha256Holder this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/hash/Hashing$Sha256Holder;
}
SourceFile: "Hashing.java"
NestHost: com.google.common.hash.Hashing
InnerClasses:
  private Sha256Holder = com.google.common.hash.Hashing$Sha256Holder of com.google.common.hash.Hashing