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. 
public abstract class com.google.common.collect.ForwardingConcurrentMap<K, V> extends com.google.common.collect.ForwardingMap<K, V> implements java.util.concurrent.ConcurrentMap<K, V>
  minor version: 0
  major version: 59
  flags: flags: (0x0421) ACC_PUBLIC, ACC_SUPER, ACC_ABSTRACT
  this_class: com.google.common.collect.ForwardingConcurrentMap
  super_class: com.google.common.collect.ForwardingMap
{
  protected void <init>();
    descriptor: ()V
    flags: (0x0004) ACC_PROTECTED
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // com.google.common.collect.ForwardingConcurrentMap this
         0: .line 43
            aload 0 /* this */
            invokespecial com.google.common.collect.ForwardingMap.<init>:()V
            return
        end local 0 // com.google.common.collect.ForwardingConcurrentMap this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/collect/ForwardingConcurrentMap<TK;TV;>;

  protected abstract java.util.concurrent.ConcurrentMap<K, V> delegate();
    descriptor: ()Ljava/util/concurrent/ConcurrentMap;
    flags: (0x0404) ACC_PROTECTED, ACC_ABSTRACT
    Signature: ()Ljava/util/concurrent/ConcurrentMap<TK;TV;>;

  public V putIfAbsent(K, );
    descriptor: (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=3, args_size=3
        start local 0 // com.google.common.collect.ForwardingConcurrentMap this
        start local 1 // java.lang.Object key
        start local 2 // java.lang.Object value
         0: .line 51
            aload 0 /* this */
            invokevirtual com.google.common.collect.ForwardingConcurrentMap.delegate:()Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* key */
            aload 2 /* value */
            invokeinterface java.util.concurrent.ConcurrentMap.putIfAbsent:(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
            areturn
        end local 2 // java.lang.Object value
        end local 1 // java.lang.Object key
        end local 0 // com.google.common.collect.ForwardingConcurrentMap this
      LocalVariableTable:
        Start  End  Slot   Name  Signature
            0    1     0   this  Lcom/google/common/collect/ForwardingConcurrentMap<TK;TV;>;
            0    1     1    key  TK;
            0    1     2  value  TV;
    Signature: (TK;TV;)TV;
    RuntimeInvisibleAnnotations: 
      com.google.errorprone.annotations.CanIgnoreReturnValue()
    MethodParameters:
       Name  Flags
      key    
      value  

  public boolean remove(java.lang.Object, java.lang.Object);
    descriptor: (Ljava/lang/Object;Ljava/lang/Object;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=3, args_size=3
        start local 0 // com.google.common.collect.ForwardingConcurrentMap this
        start local 1 // java.lang.Object key
        start local 2 // java.lang.Object value
         0: .line 57
            aload 0 /* this */
            invokevirtual com.google.common.collect.ForwardingConcurrentMap.delegate:()Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* key */
            aload 2 /* value */
            invokeinterface java.util.concurrent.ConcurrentMap.remove:(Ljava/lang/Object;Ljava/lang/Object;)Z
            ireturn
        end local 2 // java.lang.Object value
        end local 1 // java.lang.Object key
        end local 0 // com.google.common.collect.ForwardingConcurrentMap this
      LocalVariableTable:
        Start  End  Slot   Name  Signature
            0    1     0   this  Lcom/google/common/collect/ForwardingConcurrentMap<TK;TV;>;
            0    1     1    key  Ljava/lang/Object;
            0    1     2  value  Ljava/lang/Object;
    RuntimeInvisibleAnnotations: 
      com.google.errorprone.annotations.CanIgnoreReturnValue()
    MethodParameters:
       Name  Flags
      key    
      value  

  public V replace(K, );
    descriptor: (Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=3, args_size=3
        start local 0 // com.google.common.collect.ForwardingConcurrentMap this
        start local 1 // java.lang.Object key
        start local 2 // java.lang.Object value
         0: .line 63
            aload 0 /* this */
            invokevirtual com.google.common.collect.ForwardingConcurrentMap.delegate:()Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* key */
            aload 2 /* value */
            invokeinterface java.util.concurrent.ConcurrentMap.replace:(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
            areturn
        end local 2 // java.lang.Object value
        end local 1 // java.lang.Object key
        end local 0 // com.google.common.collect.ForwardingConcurrentMap this
      LocalVariableTable:
        Start  End  Slot   Name  Signature
            0    1     0   this  Lcom/google/common/collect/ForwardingConcurrentMap<TK;TV;>;
            0    1     1    key  TK;
            0    1     2  value  TV;
    Signature: (TK;TV;)TV;
    RuntimeInvisibleAnnotations: 
      com.google.errorprone.annotations.CanIgnoreReturnValue()
    MethodParameters:
       Name  Flags
      key    
      value  

  public boolean replace(K, V, );
    descriptor: (Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=4, args_size=4
        start local 0 // com.google.common.collect.ForwardingConcurrentMap this
        start local 1 // java.lang.Object key
        start local 2 // java.lang.Object oldValue
        start local 3 // java.lang.Object newValue
         0: .line 69
            aload 0 /* this */
            invokevirtual com.google.common.collect.ForwardingConcurrentMap.delegate:()Ljava/util/concurrent/ConcurrentMap;
            aload 1 /* key */
            aload 2 /* oldValue */
            aload 3 /* newValue */
            invokeinterface java.util.concurrent.ConcurrentMap.replace:(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Z
            ireturn
        end local 3 // java.lang.Object newValue
        end local 2 // java.lang.Object oldValue
        end local 1 // java.lang.Object key
        end local 0 // com.google.common.collect.ForwardingConcurrentMap this
      LocalVariableTable:
        Start  End  Slot      Name  Signature
            0    1     0      this  Lcom/google/common/collect/ForwardingConcurrentMap<TK;TV;>;
            0    1     1       key  TK;
            0    1     2  oldValue  TV;
            0    1     3  newValue  TV;
    Signature: (TK;TV;TV;)Z
    RuntimeInvisibleAnnotations: 
      com.google.errorprone.annotations.CanIgnoreReturnValue()
    MethodParameters:
          Name  Flags
      key       
      oldValue  
      newValue  

  protected java.util.Map delegate();
    descriptor: ()Ljava/util/Map;
    flags: (0x1044) ACC_PROTECTED, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=1, locals=1, args_size=1
         0: .line 1
            aload 0
            invokevirtual com.google.common.collect.ForwardingConcurrentMap.delegate:()Ljava/util/concurrent/ConcurrentMap;
            areturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature

  protected java.lang.Object delegate();
    descriptor: ()Ljava/lang/Object;
    flags: (0x1044) ACC_PROTECTED, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=1, locals=1, args_size=1
         0: .line 1
            aload 0
            invokevirtual com.google.common.collect.ForwardingConcurrentMap.delegate:()Ljava/util/concurrent/ConcurrentMap;
            areturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature
}
Signature: <K:Ljava/lang/Object;V:Ljava/lang/Object;>Lcom/google/common/collect/ForwardingMap<TK;TV;>;Ljava/util/concurrent/ConcurrentMap<TK;TV;>;
SourceFile: "ForwardingConcurrentMap.java"
    RuntimeInvisibleAnnotations: 
      com.google.common.annotations.GwtCompatible()