http://netty.io/netty-all/: Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers and clients. (The Netty Project) 
public abstract class io.netty.util.ConstantPool<T extends io.netty.util.Constant<T>>
  minor version: 0
  major version: 59
  flags: flags: (0x0421) ACC_PUBLIC, ACC_SUPER, ACC_ABSTRACT
  this_class: io.netty.util.ConstantPool
  super_class: java.lang.Object
{
  private final java.util.concurrent.ConcurrentMap<java.lang.String, T> constants;
    descriptor: Ljava/util/concurrent/ConcurrentMap;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Ljava/util/concurrent/ConcurrentMap<Ljava/lang/String;TT;>;

  private final java.util.concurrent.atomic.AtomicInteger nextId;
    descriptor: Ljava/util/concurrent/atomic/AtomicInteger;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  public void <init>();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=1, args_size=1
        start local 0 // io.netty.util.ConstantPool this
         0: .line 30
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 32
            aload 0 /* this */
            invokestatic io.netty.util.internal.PlatformDependent.newConcurrentHashMap:()Ljava/util/concurrent/ConcurrentMap;
            putfield io.netty.util.ConstantPool.constants:Ljava/util/concurrent/ConcurrentMap;
         2: .line 34
            aload 0 /* this */
            new java.util.concurrent.atomic.AtomicInteger
            dup
            iconst_1
            invokespecial java.util.concurrent.atomic.AtomicInteger.<init>:(I)V
            putfield io.netty.util.ConstantPool.nextId:Ljava/util/concurrent/atomic/AtomicInteger;
         3: .line 30
            return
        end local 0 // io.netty.util.ConstantPool this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    4     0  this  Lio/netty/util/ConstantPool<TT;>;

  public T valueOf(java.lang.Class<?>, java.lang.String);
    descriptor: (Ljava/lang/Class;Ljava/lang/String;)Lio/netty/util/Constant;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=3, args_size=3
        start local 0 // io.netty.util.ConstantPool this
        start local 1 // java.lang.Class firstNameComponent
        start local 2 // java.lang.String secondNameComponent
         0: .line 40
            aload 1 /* firstNameComponent */
            ifnonnull 2
         1: .line 41
            new java.lang.NullPointerException
            dup
            ldc "firstNameComponent"
            invokespecial java.lang.NullPointerException.<init>:(Ljava/lang/String;)V
            athrow
         2: .line 43
      StackMap locals:
      StackMap stack:
            aload 2 /* secondNameComponent */
            ifnonnull 4
         3: .line 44
            new java.lang.NullPointerException
            dup
            ldc "secondNameComponent"
            invokespecial java.lang.NullPointerException.<init>:(Ljava/lang/String;)V
            athrow
         4: .line 47
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            new java.lang.StringBuilder
            dup
            aload 1 /* firstNameComponent */
            invokevirtual java.lang.Class.getName:()Ljava/lang/String;
            invokestatic java.lang.String.valueOf:(Ljava/lang/Object;)Ljava/lang/String;
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            bipush 35
            invokevirtual java.lang.StringBuilder.append:(C)Ljava/lang/StringBuilder;
            aload 2 /* secondNameComponent */
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            invokevirtual io.netty.util.ConstantPool.valueOf:(Ljava/lang/String;)Lio/netty/util/Constant;
            areturn
        end local 2 // java.lang.String secondNameComponent
        end local 1 // java.lang.Class firstNameComponent
        end local 0 // io.netty.util.ConstantPool this
      LocalVariableTable:
        Start  End  Slot                 Name  Signature
            0    5     0                 this  Lio/netty/util/ConstantPool<TT;>;
            0    5     1   firstNameComponent  Ljava/lang/Class<*>;
            0    5     2  secondNameComponent  Ljava/lang/String;
    Signature: (Ljava/lang/Class<*>;Ljava/lang/String;)TT;
    MethodParameters:
                     Name  Flags
      firstNameComponent   
      secondNameComponent  

  public T valueOf(java.lang.String);
    descriptor: (Ljava/lang/String;)Lio/netty/util/Constant;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // io.netty.util.ConstantPool this
        start local 1 // java.lang.String name
         0: .line 59
            aload 1 /* name */
            invokestatic io.netty.util.ConstantPool.checkNotNullAndNotEmpty:(Ljava/lang/String;)Ljava/lang/String;
            pop
         1: .line 60
            aload 0 /* this */
            aload 1 /* name */
            invokevirtual io.netty.util.ConstantPool.getOrCreate:(Ljava/lang/String;)Lio/netty/util/Constant;
            areturn
        end local 1 // java.lang.String name
        end local 0 // io.netty.util.ConstantPool this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    2     0  this  Lio/netty/util/ConstantPool<TT;>;
            0    2     1  name  Ljava/lang/String;
    Signature: (Ljava/lang/String;)TT;
    MethodParameters:
      Name  Flags
      name  

  private T getOrCreate(java.lang.String);
    descriptor: (Ljava/lang/String;)Lio/netty/util/Constant;
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=3, locals=4, args_size=2
        start local 0 // io.netty.util.ConstantPool this
        start local 1 // java.lang.String name
         0: .line 69
            aload 0 /* this */
            getfield io.netty.util.ConstantPool.constants:Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* name */
            invokeinterface java.util.concurrent.ConcurrentMap.get:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast io.netty.util.Constant
            astore 2 /* constant */
        start local 2 // io.netty.util.Constant constant
         1: .line 70
            aload 2 /* constant */
            ifnonnull 6
         2: .line 71
            aload 0 /* this */
            aload 0 /* this */
            invokevirtual io.netty.util.ConstantPool.nextId:()I
            aload 1 /* name */
            invokevirtual io.netty.util.ConstantPool.newConstant:(ILjava/lang/String;)Lio/netty/util/Constant;
            astore 3 /* tempConstant */
        start local 3 // io.netty.util.Constant tempConstant
         3: .line 72
            aload 0 /* this */
            getfield io.netty.util.ConstantPool.constants:Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* name */
            aload 3 /* tempConstant */
            invokeinterface java.util.concurrent.ConcurrentMap.putIfAbsent:(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
            checkcast io.netty.util.Constant
            astore 2 /* constant */
         4: .line 73
            aload 2 /* constant */
            ifnonnull 6
         5: .line 74
            aload 3 /* tempConstant */
            areturn
        end local 3 // io.netty.util.Constant tempConstant
         6: .line 78
      StackMap locals: io.netty.util.Constant
      StackMap stack:
            aload 2 /* constant */
            areturn
        end local 2 // io.netty.util.Constant constant
        end local 1 // java.lang.String name
        end local 0 // io.netty.util.ConstantPool this
      LocalVariableTable:
        Start  End  Slot          Name  Signature
            0    7     0          this  Lio/netty/util/ConstantPool<TT;>;
            0    7     1          name  Ljava/lang/String;
            1    7     2      constant  TT;
            3    6     3  tempConstant  TT;
    Signature: (Ljava/lang/String;)TT;
    MethodParameters:
      Name  Flags
      name  

  public boolean exists(java.lang.String);
    descriptor: (Ljava/lang/String;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // io.netty.util.ConstantPool this
        start local 1 // java.lang.String name
         0: .line 85
            aload 1 /* name */
            invokestatic io.netty.util.ConstantPool.checkNotNullAndNotEmpty:(Ljava/lang/String;)Ljava/lang/String;
            pop
         1: .line 86
            aload 0 /* this */
            getfield io.netty.util.ConstantPool.constants:Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* name */
            invokeinterface java.util.concurrent.ConcurrentMap.containsKey:(Ljava/lang/Object;)Z
            ireturn
        end local 1 // java.lang.String name
        end local 0 // io.netty.util.ConstantPool this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    2     0  this  Lio/netty/util/ConstantPool<TT;>;
            0    2     1  name  Ljava/lang/String;
    MethodParameters:
      Name  Flags
      name  

  public T newInstance(java.lang.String);
    descriptor: (Ljava/lang/String;)Lio/netty/util/Constant;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // io.netty.util.ConstantPool this
        start local 1 // java.lang.String name
         0: .line 94
            aload 1 /* name */
            invokestatic io.netty.util.ConstantPool.checkNotNullAndNotEmpty:(Ljava/lang/String;)Ljava/lang/String;
            pop
         1: .line 95
            aload 0 /* this */
            aload 1 /* name */
            invokevirtual io.netty.util.ConstantPool.createOrThrow:(Ljava/lang/String;)Lio/netty/util/Constant;
            areturn
        end local 1 // java.lang.String name
        end local 0 // io.netty.util.ConstantPool this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    2     0  this  Lio/netty/util/ConstantPool<TT;>;
            0    2     1  name  Ljava/lang/String;
    Signature: (Ljava/lang/String;)TT;
    MethodParameters:
      Name  Flags
      name  

  private T createOrThrow(java.lang.String);
    descriptor: (Ljava/lang/String;)Lio/netty/util/Constant;
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=7, locals=4, args_size=2
        start local 0 // io.netty.util.ConstantPool this
        start local 1 // java.lang.String name
         0: .line 104
            aload 0 /* this */
            getfield io.netty.util.ConstantPool.constants:Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* name */
            invokeinterface java.util.concurrent.ConcurrentMap.get:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast io.netty.util.Constant
            astore 2 /* constant */
        start local 2 // io.netty.util.Constant constant
         1: .line 105
            aload 2 /* constant */
            ifnonnull 6
         2: .line 106
            aload 0 /* this */
            aload 0 /* this */
            invokevirtual io.netty.util.ConstantPool.nextId:()I
            aload 1 /* name */
            invokevirtual io.netty.util.ConstantPool.newConstant:(ILjava/lang/String;)Lio/netty/util/Constant;
            astore 3 /* tempConstant */
        start local 3 // io.netty.util.Constant tempConstant
         3: .line 107
            aload 0 /* this */
            getfield io.netty.util.ConstantPool.constants:Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* name */
            aload 3 /* tempConstant */
            invokeinterface java.util.concurrent.ConcurrentMap.putIfAbsent:(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
            checkcast io.netty.util.Constant
            astore 2 /* constant */
         4: .line 108
            aload 2 /* constant */
            ifnonnull 6
         5: .line 109
            aload 3 /* tempConstant */
            areturn
        end local 3 // io.netty.util.Constant tempConstant
         6: .line 113
      StackMap locals: io.netty.util.Constant
      StackMap stack:
            new java.lang.IllegalArgumentException
            dup
            ldc "'%s' is already in use"
            iconst_1
            anewarray java.lang.Object
            dup
            iconst_0
            aload 1 /* name */
            aastore
            invokestatic java.lang.String.format:(Ljava/lang/String;[Ljava/lang/Object;)Ljava/lang/String;
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
        end local 2 // io.netty.util.Constant constant
        end local 1 // java.lang.String name
        end local 0 // io.netty.util.ConstantPool this
      LocalVariableTable:
        Start  End  Slot          Name  Signature
            0    7     0          this  Lio/netty/util/ConstantPool<TT;>;
            0    7     1          name  Ljava/lang/String;
            1    7     2      constant  TT;
            3    6     3  tempConstant  TT;
    Signature: (Ljava/lang/String;)TT;
    MethodParameters:
      Name  Flags
      name  

  private static java.lang.String checkNotNullAndNotEmpty(java.lang.String);
    descriptor: (Ljava/lang/String;)Ljava/lang/String;
    flags: (0x000a) ACC_PRIVATE, ACC_STATIC
    Code:
      stack=3, locals=1, args_size=1
        start local 0 // java.lang.String name
         0: .line 117
            aload 0 /* name */
            ldc "name"
            invokestatic io.netty.util.internal.ObjectUtil.checkNotNull:(Ljava/lang/Object;Ljava/lang/String;)Ljava/lang/Object;
            pop
         1: .line 119
            aload 0 /* name */
            invokevirtual java.lang.String.isEmpty:()Z
            ifeq 3
         2: .line 120
            new java.lang.IllegalArgumentException
            dup
            ldc "empty name"
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
         3: .line 123
      StackMap locals:
      StackMap stack:
            aload 0 /* name */
            areturn
        end local 0 // java.lang.String name
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    4     0  name  Ljava/lang/String;
    MethodParameters:
      Name  Flags
      name  

  protected abstract T newConstant(int, java.lang.String);
    descriptor: (ILjava/lang/String;)Lio/netty/util/Constant;
    flags: (0x0404) ACC_PROTECTED, ACC_ABSTRACT
    Signature: (ILjava/lang/String;)TT;
    MethodParameters:
      Name  Flags
      id    
      name  

  public final int nextId();
    descriptor: ()I
    flags: (0x0011) ACC_PUBLIC, ACC_FINAL
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // io.netty.util.ConstantPool this
         0: .line 130
            aload 0 /* this */
            getfield io.netty.util.ConstantPool.nextId:Ljava/util/concurrent/atomic/AtomicInteger;
            invokevirtual java.util.concurrent.atomic.AtomicInteger.getAndIncrement:()I
            ireturn
        end local 0 // io.netty.util.ConstantPool this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lio/netty/util/ConstantPool<TT;>;
    RuntimeVisibleAnnotations: 
      java.lang.Deprecated()
}
Signature: <T::Lio/netty/util/Constant<TT;>;>Ljava/lang/Object;
SourceFile: "ConstantPool.java"