https://github.com/eclipse/eclipse-collections/eclipse-collections-api: Eclipse Collections is a collections framework for Java. It has JDK-compatible List, Set and Map implementations with a rich API and set of utility classes that work with any JDK compatible Collections, Arrays, Maps or Strings. The iteration protocol was inspired by the Smalltalk collection framework.
  • Craig P. Motlin
  • Donald Raab
  • Mohammad A. Rezaei
  • Hiroshi Ito
  • Nikhil J. Nanivadekar 
public interface org.eclipse.collections.api.tuple.Pair<T1, T2> extends java.io.Serializable, java.lang.Comparable<org.eclipse.collections.api.tuple.Pair<T1, T2>>
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: org.eclipse.collections.api.tuple.Pair
  super_class: java.lang.Object
{
  public abstract T1 getOne();
    descriptor: ()Ljava/lang/Object;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()TT1;

  public abstract T2 getTwo();
    descriptor: ()Ljava/lang/Object;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()TT2;

  public abstract void put(java.util.Map<? super T1, ? super T2>);
    descriptor: (Ljava/util/Map;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: (Ljava/util/Map<-TT1;-TT2;>;)V
    MethodParameters:
      Name  Flags
      map   

  public abstract java.util.Map$Entry<T1, T2> toEntry();
    descriptor: ()Ljava/util/Map$Entry;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()Ljava/util/Map$Entry<TT1;TT2;>;

  public abstract org.eclipse.collections.api.tuple.Pair<T2, T1> swap();
    descriptor: ()Lorg/eclipse/collections/api/tuple/Pair;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()Lorg/eclipse/collections/api/tuple/Pair<TT2;TT1;>;
}
Signature: <T1:Ljava/lang/Object;T2:Ljava/lang/Object;>Ljava/lang/Object;Ljava/io/Serializable;Ljava/lang/Comparable<Lorg/eclipse/collections/api/tuple/Pair<TT1;TT2;>;>;
SourceFile: "Pair.java"
InnerClasses:
  public abstract Entry = java.util.Map$Entry of java.util.Map