https://github.com/eclipse/eclipse-collections/eclipse-collections: 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 
class org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView extends org.eclipse.collections.impl.lazy.primitive.AbstractLazyIntIterable
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView
  super_class: org.eclipse.collections.impl.lazy.primitive.AbstractLazyIntIterable
{
  final org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap this$0;
    descriptor: Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  private void <init>(org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap);
    descriptor: (Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap;)V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView this
         0: .line 1376
            aload 0 /* this */
            aload 1
            putfield org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView.this$0:Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap;
            aload 0 /* this */
            invokespecial org.eclipse.collections.impl.lazy.primitive.AbstractLazyIntIterable.<init>:()V
            return
        end local 0 // org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap$KeysView;
    MethodParameters:
        Name  Flags
      this$0  final

  public org.eclipse.collections.api.iterator.IntIterator intIterator();
    descriptor: ()Lorg/eclipse/collections/api/iterator/IntIterator;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=1, args_size=1
        start local 0 // org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView this
         0: .line 1381
            new org.eclipse.collections.impl.iterator.UnmodifiableIntIterator
            dup
            new org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeySetIterator
            dup
            aload 0 /* this */
            getfield org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView.this$0:Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap;
            invokespecial org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeySetIterator.<init>:(Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap;)V
            invokespecial org.eclipse.collections.impl.iterator.UnmodifiableIntIterator.<init>:(Lorg/eclipse/collections/api/iterator/IntIterator;)V
            areturn
        end local 0 // org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap$KeysView;

  public void each(org.eclipse.collections.api.block.procedure.primitive.IntProcedure);
    descriptor: (Lorg/eclipse/collections/api/block/procedure/primitive/IntProcedure;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView this
        start local 1 // org.eclipse.collections.api.block.procedure.primitive.IntProcedure procedure
         0: .line 1390
            aload 0 /* this */
            getfield org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView.this$0:Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap;
            aload 1 /* procedure */
            invokevirtual org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap.forEachKey:(Lorg/eclipse/collections/api/block/procedure/primitive/IntProcedure;)V
         1: .line 1391
            return
        end local 1 // org.eclipse.collections.api.block.procedure.primitive.IntProcedure procedure
        end local 0 // org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    2     0       this  Lorg/eclipse/collections/impl/map/mutable/primitive/IntIntHashMap$KeysView;
            0    2     1  procedure  Lorg/eclipse/collections/api/block/procedure/primitive/IntProcedure;
    MethodParameters:
           Name  Flags
      procedure  
}
SourceFile: "IntIntHashMap.java"
NestHost: org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap
InnerClasses:
  private KeySetIterator = org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeySetIterator of org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap
  private KeysView = org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap$KeysView of org.eclipse.collections.impl.map.mutable.primitive.IntIntHashMap