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. 
final class com.google.common.hash.MacHashFunction extends com.google.common.hash.AbstractHashFunction
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.google.common.hash.MacHashFunction
  super_class: com.google.common.hash.AbstractHashFunction
{
  private final javax.crypto.Mac prototype;
    descriptor: Ljavax/crypto/Mac;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final java.security.Key key;
    descriptor: Ljava/security/Key;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final java.lang.String toString;
    descriptor: Ljava/lang/String;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final int bits;
    descriptor: I
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final boolean supportsClone;
    descriptor: Z
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  void <init>(java.lang.String, java.security.Key, java.lang.String);
    descriptor: (Ljava/lang/String;Ljava/security/Key;Ljava/lang/String;)V
    flags: (0x0000) 
    Code:
      stack=3, locals=4, args_size=4
        start local 0 // com.google.common.hash.MacHashFunction this
        start local 1 // java.lang.String algorithmName
        start local 2 // java.security.Key key
        start local 3 // java.lang.String toString
         0: .line 43
            aload 0 /* this */
            invokespecial com.google.common.hash.AbstractHashFunction.<init>:()V
         1: .line 44
            aload 0 /* this */
            aload 1 /* algorithmName */
            aload 2 /* key */
            invokestatic com.google.common.hash.MacHashFunction.getMac:(Ljava/lang/String;Ljava/security/Key;)Ljavax/crypto/Mac;
            putfield com.google.common.hash.MacHashFunction.prototype:Ljavax/crypto/Mac;
         2: .line 45
            aload 0 /* this */
            aload 2 /* key */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast java.security.Key
            putfield com.google.common.hash.MacHashFunction.key:Ljava/security/Key;
         3: .line 46
            aload 0 /* this */
            aload 3 /* toString */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast java.lang.String
            putfield com.google.common.hash.MacHashFunction.toString:Ljava/lang/String;
         4: .line 47
            aload 0 /* this */
            aload 0 /* this */
            getfield com.google.common.hash.MacHashFunction.prototype:Ljavax/crypto/Mac;
            invokevirtual javax.crypto.Mac.getMacLength:()I
            bipush 8
            imul
            putfield com.google.common.hash.MacHashFunction.bits:I
         5: .line 48
            aload 0 /* this */
            aload 0 /* this */
            getfield com.google.common.hash.MacHashFunction.prototype:Ljavax/crypto/Mac;
            invokestatic com.google.common.hash.MacHashFunction.supportsClone:(Ljavax/crypto/Mac;)Z
            putfield com.google.common.hash.MacHashFunction.supportsClone:Z
         6: .line 49
            return
        end local 3 // java.lang.String toString
        end local 2 // java.security.Key key
        end local 1 // java.lang.String algorithmName
        end local 0 // com.google.common.hash.MacHashFunction this
      LocalVariableTable:
        Start  End  Slot           Name  Signature
            0    7     0           this  Lcom/google/common/hash/MacHashFunction;
            0    7     1  algorithmName  Ljava/lang/String;
            0    7     2            key  Ljava/security/Key;
            0    7     3       toString  Ljava/lang/String;
    MethodParameters:
               Name  Flags
      algorithmName  
      key            
      toString       

  public int bits();
    descriptor: ()I
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.google.common.hash.MacHashFunction this
         0: .line 53
            aload 0 /* this */
            getfield com.google.common.hash.MacHashFunction.bits:I
            ireturn
        end local 0 // com.google.common.hash.MacHashFunction this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/hash/MacHashFunction;

  private static boolean supportsClone(javax.crypto.Mac);
    descriptor: (Ljavax/crypto/Mac;)Z
    flags: (0x000a) ACC_PRIVATE, ACC_STATIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // javax.crypto.Mac mac
         0: .line 58
            aload 0 /* mac */
            invokevirtual javax.crypto.Mac.clone:()Ljava/lang/Object;
            pop
         1: .line 59
            iconst_1
            ireturn
         2: .line 60
      StackMap locals:
      StackMap stack: java.lang.CloneNotSupportedException
            pop
         3: .line 61
            iconst_0
            ireturn
        end local 0 // javax.crypto.Mac mac
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    4     0   mac  Ljavax/crypto/Mac;
      Exception table:
        from    to  target  type
           0     1       2  Class java.lang.CloneNotSupportedException
    MethodParameters:
      Name  Flags
      mac   

  private static javax.crypto.Mac getMac(java.lang.String, java.security.Key);
    descriptor: (Ljava/lang/String;Ljava/security/Key;)Ljavax/crypto/Mac;
    flags: (0x000a) ACC_PRIVATE, ACC_STATIC
    Code:
      stack=3, locals=3, args_size=2
        start local 0 // java.lang.String algorithmName
        start local 1 // java.security.Key key
         0: .line 67
            aload 0 /* algorithmName */
            invokestatic javax.crypto.Mac.getInstance:(Ljava/lang/String;)Ljavax/crypto/Mac;
            astore 2 /* mac */
        start local 2 // javax.crypto.Mac mac
         1: .line 68
            aload 2 /* mac */
            aload 1 /* key */
            invokevirtual javax.crypto.Mac.init:(Ljava/security/Key;)V
         2: .line 69
            aload 2 /* mac */
         3: areturn
        end local 2 // javax.crypto.Mac mac
         4: .line 70
      StackMap locals:
      StackMap stack: java.security.NoSuchAlgorithmException
            astore 2 /* e */
        start local 2 // java.security.NoSuchAlgorithmException e
         5: .line 71
            new java.lang.IllegalStateException
            dup
            aload 2 /* e */
            invokespecial java.lang.IllegalStateException.<init>:(Ljava/lang/Throwable;)V
            athrow
        end local 2 // java.security.NoSuchAlgorithmException e
         6: .line 72
      StackMap locals:
      StackMap stack: java.security.InvalidKeyException
            astore 2 /* e */
        start local 2 // java.security.InvalidKeyException e
         7: .line 73
            new java.lang.IllegalArgumentException
            dup
            aload 2 /* e */
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/Throwable;)V
            athrow
        end local 2 // java.security.InvalidKeyException e
        end local 1 // java.security.Key key
        end local 0 // java.lang.String algorithmName
      LocalVariableTable:
        Start  End  Slot           Name  Signature
            0    8     0  algorithmName  Ljava/lang/String;
            0    8     1            key  Ljava/security/Key;
            1    4     2            mac  Ljavax/crypto/Mac;
            5    6     2              e  Ljava/security/NoSuchAlgorithmException;
            7    8     2              e  Ljava/security/InvalidKeyException;
      Exception table:
        from    to  target  type
           0     3       4  Class java.security.NoSuchAlgorithmException
           0     3       6  Class java.security.InvalidKeyException
    MethodParameters:
               Name  Flags
      algorithmName  
      key            

  public com.google.common.hash.Hasher newHasher();
    descriptor: ()Lcom/google/common/hash/Hasher;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=1, args_size=1
        start local 0 // com.google.common.hash.MacHashFunction this
         0: .line 79
            aload 0 /* this */
            getfield com.google.common.hash.MacHashFunction.supportsClone:Z
            ifeq 4
         1: .line 81
            new com.google.common.hash.MacHashFunction$MacHasher
            dup
            aload 0 /* this */
            getfield com.google.common.hash.MacHashFunction.prototype:Ljavax/crypto/Mac;
            invokevirtual javax.crypto.Mac.clone:()Ljava/lang/Object;
            checkcast javax.crypto.Mac
            invokespecial com.google.common.hash.MacHashFunction$MacHasher.<init>:(Ljavax/crypto/Mac;)V
         2: areturn
         3: .line 82
      StackMap locals:
      StackMap stack: java.lang.CloneNotSupportedException
            pop
         4: .line 86
      StackMap locals:
      StackMap stack:
            new com.google.common.hash.MacHashFunction$MacHasher
            dup
            aload 0 /* this */
            getfield com.google.common.hash.MacHashFunction.prototype:Ljavax/crypto/Mac;
            invokevirtual javax.crypto.Mac.getAlgorithm:()Ljava/lang/String;
            aload 0 /* this */
            getfield com.google.common.hash.MacHashFunction.key:Ljava/security/Key;
            invokestatic com.google.common.hash.MacHashFunction.getMac:(Ljava/lang/String;Ljava/security/Key;)Ljavax/crypto/Mac;
            invokespecial com.google.common.hash.MacHashFunction$MacHasher.<init>:(Ljavax/crypto/Mac;)V
            areturn
        end local 0 // com.google.common.hash.MacHashFunction this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    5     0  this  Lcom/google/common/hash/MacHashFunction;
      Exception table:
        from    to  target  type
           1     2       3  Class java.lang.CloneNotSupportedException

  public java.lang.String toString();
    descriptor: ()Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.google.common.hash.MacHashFunction this
         0: .line 91
            aload 0 /* this */
            getfield com.google.common.hash.MacHashFunction.toString:Ljava/lang/String;
            areturn
        end local 0 // com.google.common.hash.MacHashFunction this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/hash/MacHashFunction;
}
SourceFile: "MacHashFunction.java"
NestMembers:
  com.google.common.hash.MacHashFunction$MacHasher
InnerClasses:
  private final MacHasher = com.google.common.hash.MacHashFunction$MacHasher of com.google.common.hash.MacHashFunction
    RuntimeVisibleAnnotations: 
      com.google.errorprone.annotations.Immutable()