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. 
class com.google.common.graph.Traverser$GraphTraverser$2 implements java.lang.Iterable<N>
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.google.common.graph.Traverser$GraphTraverser$2
  super_class: java.lang.Object
{
  final com.google.common.graph.Traverser$GraphTraverser this$1;
    descriptor: Lcom/google/common/graph/Traverser$GraphTraverser;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  private final java.lang.Iterable val$startNodes;
    descriptor: Ljava/lang/Iterable;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  void <init>(com.google.common.graph.Traverser$GraphTraverser, java.lang.Iterable);
    descriptor: (Lcom/google/common/graph/Traverser$GraphTraverser;Ljava/lang/Iterable;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=3, args_size=3
        start local 0 // com.google.common.graph.Traverser$GraphTraverser$2 this
         0: .line 364
            aload 0 /* this */
            aload 1
            putfield com.google.common.graph.Traverser$GraphTraverser$2.this$1:Lcom/google/common/graph/Traverser$GraphTraverser;
            aload 0 /* this */
            aload 2
            putfield com.google.common.graph.Traverser$GraphTraverser$2.val$startNodes:Ljava/lang/Iterable;
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // com.google.common.graph.Traverser$GraphTraverser$2 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/graph/Traverser$GraphTraverser$2;
    MethodParameters:
                Name  Flags
      this$0          final
      val$startNodes  final

  public java.util.Iterator<N> iterator();
    descriptor: ()Ljava/util/Iterator;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=1, args_size=1
        start local 0 // com.google.common.graph.Traverser$GraphTraverser$2 this
         0: .line 367
            new com.google.common.graph.Traverser$GraphTraverser$DepthFirstIterator
            dup
            aload 0 /* this */
            getfield com.google.common.graph.Traverser$GraphTraverser$2.this$1:Lcom/google/common/graph/Traverser$GraphTraverser;
            aload 0 /* this */
            getfield com.google.common.graph.Traverser$GraphTraverser$2.val$startNodes:Ljava/lang/Iterable;
            getstatic com.google.common.graph.Traverser$Order.PREORDER:Lcom/google/common/graph/Traverser$Order;
            invokespecial com.google.common.graph.Traverser$GraphTraverser$DepthFirstIterator.<init>:(Lcom/google/common/graph/Traverser$GraphTraverser;Ljava/lang/Iterable;Lcom/google/common/graph/Traverser$Order;)V
            areturn
        end local 0 // com.google.common.graph.Traverser$GraphTraverser$2 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/google/common/graph/Traverser$GraphTraverser$2;
    Signature: ()Ljava/util/Iterator<TN;>;
}
Signature: Ljava/lang/Object;Ljava/lang/Iterable<TN;>;
SourceFile: "Traverser.java"
EnclosingMethod: com.google.common.graph.Traverser$GraphTraverser.depthFirstPreOrder:(Ljava/lang/Iterable;)Ljava/lang/Iterable;
NestHost: com.google.common.graph.Traverser
InnerClasses:
  private final GraphTraverser = com.google.common.graph.Traverser$GraphTraverser of com.google.common.graph.Traverser
  com.google.common.graph.Traverser$GraphTraverser$2
  private final DepthFirstIterator = com.google.common.graph.Traverser$GraphTraverser$DepthFirstIterator of com.google.common.graph.Traverser$GraphTraverser
  private final Order = com.google.common.graph.Traverser$Order of com.google.common.graph.Traverser