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. 
final class com.google.common.graph.Traverser$TreeTraverser<N> extends com.google.common.graph.Traverser<N>
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: com.google.common.graph.Traverser$TreeTraverser
  super_class: com.google.common.graph.Traverser
{
  private final com.google.common.graph.SuccessorsFunction<N> tree;
    descriptor: Lcom/google/common/graph/SuccessorsFunction;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL
    Signature: Lcom/google/common/graph/SuccessorsFunction<TN;>;

  void <init>(com.google.common.graph.SuccessorsFunction<N>);
    descriptor: (Lcom/google/common/graph/SuccessorsFunction;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.graph.Traverser$TreeTraverser this
        start local 1 // com.google.common.graph.SuccessorsFunction tree
         0: .line 488
            aload 0 /* this */
            invokespecial com.google.common.graph.Traverser.<init>:()V
         1: .line 489
            aload 0 /* this */
            aload 1 /* tree */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            checkcast com.google.common.graph.SuccessorsFunction
            putfield com.google.common.graph.Traverser$TreeTraverser.tree:Lcom/google/common/graph/SuccessorsFunction;
         2: .line 490
            return
        end local 1 // com.google.common.graph.SuccessorsFunction tree
        end local 0 // com.google.common.graph.Traverser$TreeTraverser this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    3     0  this  Lcom/google/common/graph/Traverser$TreeTraverser<TN;>;
            0    3     1  tree  Lcom/google/common/graph/SuccessorsFunction<TN;>;
    Signature: (Lcom/google/common/graph/SuccessorsFunction<TN;>;)V
    MethodParameters:
      Name  Flags
      tree  

  public java.lang.Iterable<N> breadthFirst(N);
    descriptor: (Ljava/lang/Object;)Ljava/lang/Iterable;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.graph.Traverser$TreeTraverser this
        start local 1 // java.lang.Object startNode
         0: .line 494
            aload 1 /* startNode */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            pop
         1: .line 495
            aload 0 /* this */
            aload 1 /* startNode */
            invokestatic com.google.common.collect.ImmutableSet.of:(Ljava/lang/Object;)Lcom/google/common/collect/ImmutableSet;
            invokevirtual com.google.common.graph.Traverser$TreeTraverser.breadthFirst:(Ljava/lang/Iterable;)Ljava/lang/Iterable;
            areturn
        end local 1 // java.lang.Object startNode
        end local 0 // com.google.common.graph.Traverser$TreeTraverser this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    2     0       this  Lcom/google/common/graph/Traverser$TreeTraverser<TN;>;
            0    2     1  startNode  TN;
    Signature: (TN;)Ljava/lang/Iterable<TN;>;
    MethodParameters:
           Name  Flags
      startNode  final

  public java.lang.Iterable<N> breadthFirst(java.lang.Iterable<? extends N>);
    descriptor: (Ljava/lang/Iterable;)Ljava/lang/Iterable;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=4, args_size=2
        start local 0 // com.google.common.graph.Traverser$TreeTraverser this
        start local 1 // java.lang.Iterable startNodes
         0: .line 500
            aload 1 /* startNodes */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            pop
         1: .line 501
            aload 1 /* startNodes */
            invokestatic com.google.common.collect.Iterables.isEmpty:(Ljava/lang/Iterable;)Z
            ifeq 3
         2: .line 502
            invokestatic com.google.common.collect.ImmutableSet.of:()Lcom/google/common/collect/ImmutableSet;
            areturn
         3: .line 504
      StackMap locals:
      StackMap stack:
            aload 1 /* startNodes */
            invokeinterface java.lang.Iterable.iterator:()Ljava/util/Iterator;
            astore 3
            goto 6
      StackMap locals: com.google.common.graph.Traverser$TreeTraverser java.lang.Iterable top java.util.Iterator
      StackMap stack:
         4: aload 3
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast java.lang.Object
            astore 2 /* startNode */
        start local 2 // java.lang.Object startNode
         5: .line 505
            aload 0 /* this */
            aload 2 /* startNode */
            invokevirtual com.google.common.graph.Traverser$TreeTraverser.checkThatNodeIsInTree:(Ljava/lang/Object;)V
        end local 2 // java.lang.Object startNode
         6: .line 504
      StackMap locals:
      StackMap stack:
            aload 3
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 4
         7: .line 507
            new com.google.common.graph.Traverser$TreeTraverser$1
            dup
            aload 0 /* this */
            aload 1 /* startNodes */
            invokespecial com.google.common.graph.Traverser$TreeTraverser$1.<init>:(Lcom/google/common/graph/Traverser$TreeTraverser;Ljava/lang/Iterable;)V
            areturn
        end local 1 // java.lang.Iterable startNodes
        end local 0 // com.google.common.graph.Traverser$TreeTraverser this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0    8     0        this  Lcom/google/common/graph/Traverser$TreeTraverser<TN;>;
            0    8     1  startNodes  Ljava/lang/Iterable<+TN;>;
            5    6     2   startNode  TN;
    Signature: (Ljava/lang/Iterable<+TN;>;)Ljava/lang/Iterable<TN;>;
    MethodParameters:
            Name  Flags
      startNodes  final

  public java.lang.Iterable<N> depthFirstPreOrder(N);
    descriptor: (Ljava/lang/Object;)Ljava/lang/Iterable;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.graph.Traverser$TreeTraverser this
        start local 1 // java.lang.Object startNode
         0: .line 517
            aload 1 /* startNode */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            pop
         1: .line 518
            aload 0 /* this */
            aload 1 /* startNode */
            invokestatic com.google.common.collect.ImmutableSet.of:(Ljava/lang/Object;)Lcom/google/common/collect/ImmutableSet;
            invokevirtual com.google.common.graph.Traverser$TreeTraverser.depthFirstPreOrder:(Ljava/lang/Iterable;)Ljava/lang/Iterable;
            areturn
        end local 1 // java.lang.Object startNode
        end local 0 // com.google.common.graph.Traverser$TreeTraverser this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    2     0       this  Lcom/google/common/graph/Traverser$TreeTraverser<TN;>;
            0    2     1  startNode  TN;
    Signature: (TN;)Ljava/lang/Iterable<TN;>;
    MethodParameters:
           Name  Flags
      startNode  final

  public java.lang.Iterable<N> depthFirstPreOrder(java.lang.Iterable<? extends N>);
    descriptor: (Ljava/lang/Iterable;)Ljava/lang/Iterable;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=4, args_size=2
        start local 0 // com.google.common.graph.Traverser$TreeTraverser this
        start local 1 // java.lang.Iterable startNodes
         0: .line 523
            aload 1 /* startNodes */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            pop
         1: .line 524
            aload 1 /* startNodes */
            invokestatic com.google.common.collect.Iterables.isEmpty:(Ljava/lang/Iterable;)Z
            ifeq 3
         2: .line 525
            invokestatic com.google.common.collect.ImmutableSet.of:()Lcom/google/common/collect/ImmutableSet;
            areturn
         3: .line 527
      StackMap locals:
      StackMap stack:
            aload 1 /* startNodes */
            invokeinterface java.lang.Iterable.iterator:()Ljava/util/Iterator;
            astore 3
            goto 6
      StackMap locals: com.google.common.graph.Traverser$TreeTraverser java.lang.Iterable top java.util.Iterator
      StackMap stack:
         4: aload 3
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast java.lang.Object
            astore 2 /* node */
        start local 2 // java.lang.Object node
         5: .line 528
            aload 0 /* this */
            aload 2 /* node */
            invokevirtual com.google.common.graph.Traverser$TreeTraverser.checkThatNodeIsInTree:(Ljava/lang/Object;)V
        end local 2 // java.lang.Object node
         6: .line 527
      StackMap locals:
      StackMap stack:
            aload 3
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 4
         7: .line 530
            new com.google.common.graph.Traverser$TreeTraverser$2
            dup
            aload 0 /* this */
            aload 1 /* startNodes */
            invokespecial com.google.common.graph.Traverser$TreeTraverser$2.<init>:(Lcom/google/common/graph/Traverser$TreeTraverser;Ljava/lang/Iterable;)V
            areturn
        end local 1 // java.lang.Iterable startNodes
        end local 0 // com.google.common.graph.Traverser$TreeTraverser this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0    8     0        this  Lcom/google/common/graph/Traverser$TreeTraverser<TN;>;
            0    8     1  startNodes  Ljava/lang/Iterable<+TN;>;
            5    6     2        node  TN;
    Signature: (Ljava/lang/Iterable<+TN;>;)Ljava/lang/Iterable<TN;>;
    MethodParameters:
            Name  Flags
      startNodes  final

  public java.lang.Iterable<N> depthFirstPostOrder(N);
    descriptor: (Ljava/lang/Object;)Ljava/lang/Iterable;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.graph.Traverser$TreeTraverser this
        start local 1 // java.lang.Object startNode
         0: .line 540
            aload 1 /* startNode */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            pop
         1: .line 541
            aload 0 /* this */
            aload 1 /* startNode */
            invokestatic com.google.common.collect.ImmutableSet.of:(Ljava/lang/Object;)Lcom/google/common/collect/ImmutableSet;
            invokevirtual com.google.common.graph.Traverser$TreeTraverser.depthFirstPostOrder:(Ljava/lang/Iterable;)Ljava/lang/Iterable;
            areturn
        end local 1 // java.lang.Object startNode
        end local 0 // com.google.common.graph.Traverser$TreeTraverser this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    2     0       this  Lcom/google/common/graph/Traverser$TreeTraverser<TN;>;
            0    2     1  startNode  TN;
    Signature: (TN;)Ljava/lang/Iterable<TN;>;
    MethodParameters:
           Name  Flags
      startNode  final

  public java.lang.Iterable<N> depthFirstPostOrder(java.lang.Iterable<? extends N>);
    descriptor: (Ljava/lang/Iterable;)Ljava/lang/Iterable;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=4, args_size=2
        start local 0 // com.google.common.graph.Traverser$TreeTraverser this
        start local 1 // java.lang.Iterable startNodes
         0: .line 546
            aload 1 /* startNodes */
            invokestatic com.google.common.base.Preconditions.checkNotNull:(Ljava/lang/Object;)Ljava/lang/Object;
            pop
         1: .line 547
            aload 1 /* startNodes */
            invokestatic com.google.common.collect.Iterables.isEmpty:(Ljava/lang/Iterable;)Z
            ifeq 3
         2: .line 548
            invokestatic com.google.common.collect.ImmutableSet.of:()Lcom/google/common/collect/ImmutableSet;
            areturn
         3: .line 550
      StackMap locals:
      StackMap stack:
            aload 1 /* startNodes */
            invokeinterface java.lang.Iterable.iterator:()Ljava/util/Iterator;
            astore 3
            goto 6
      StackMap locals: com.google.common.graph.Traverser$TreeTraverser java.lang.Iterable top java.util.Iterator
      StackMap stack:
         4: aload 3
            invokeinterface java.util.Iterator.next:()Ljava/lang/Object;
            checkcast java.lang.Object
            astore 2 /* startNode */
        start local 2 // java.lang.Object startNode
         5: .line 551
            aload 0 /* this */
            aload 2 /* startNode */
            invokevirtual com.google.common.graph.Traverser$TreeTraverser.checkThatNodeIsInTree:(Ljava/lang/Object;)V
        end local 2 // java.lang.Object startNode
         6: .line 550
      StackMap locals:
      StackMap stack:
            aload 3
            invokeinterface java.util.Iterator.hasNext:()Z
            ifne 4
         7: .line 553
            new com.google.common.graph.Traverser$TreeTraverser$3
            dup
            aload 0 /* this */
            aload 1 /* startNodes */
            invokespecial com.google.common.graph.Traverser$TreeTraverser$3.<init>:(Lcom/google/common/graph/Traverser$TreeTraverser;Ljava/lang/Iterable;)V
            areturn
        end local 1 // java.lang.Iterable startNodes
        end local 0 // com.google.common.graph.Traverser$TreeTraverser this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0    8     0        this  Lcom/google/common/graph/Traverser$TreeTraverser<TN;>;
            0    8     1  startNodes  Ljava/lang/Iterable<+TN;>;
            5    6     2   startNode  TN;
    Signature: (Ljava/lang/Iterable<+TN;>;)Ljava/lang/Iterable<TN;>;
    MethodParameters:
            Name  Flags
      startNodes  final

  private void checkThatNodeIsInTree();
    descriptor: (Ljava/lang/Object;)V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // com.google.common.graph.Traverser$TreeTraverser this
        start local 1 // java.lang.Object startNode
         0: .line 565
            aload 0 /* this */
            getfield com.google.common.graph.Traverser$TreeTraverser.tree:Lcom/google/common/graph/SuccessorsFunction;
            aload 1 /* startNode */
            invokeinterface com.google.common.graph.SuccessorsFunction.successors:(Ljava/lang/Object;)Ljava/lang/Iterable;
            pop
         1: .line 566
            return
        end local 1 // java.lang.Object startNode
        end local 0 // com.google.common.graph.Traverser$TreeTraverser this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    2     0       this  Lcom/google/common/graph/Traverser$TreeTraverser<TN;>;
            0    2     1  startNode  TN;
    Signature: (TN;)V
    MethodParameters:
           Name  Flags
      startNode  
}
Signature: <N:Ljava/lang/Object;>Lcom/google/common/graph/Traverser<TN;>;
SourceFile: "Traverser.java"
NestHost: com.google.common.graph.Traverser
InnerClasses:
  private final TreeTraverser = com.google.common.graph.Traverser$TreeTraverser of com.google.common.graph.Traverser
  com.google.common.graph.Traverser$TreeTraverser$1
  com.google.common.graph.Traverser$TreeTraverser$2
  com.google.common.graph.Traverser$TreeTraverser$3
  private final BreadthFirstIterator = com.google.common.graph.Traverser$TreeTraverser$BreadthFirstIterator of com.google.common.graph.Traverser$TreeTraverser
  private final DepthFirstPostOrderIterator = com.google.common.graph.Traverser$TreeTraverser$DepthFirstPostOrderIterator of com.google.common.graph.Traverser$TreeTraverser
  private final DepthFirstPreOrderIterator = com.google.common.graph.Traverser$TreeTraverser$DepthFirstPreOrderIterator of com.google.common.graph.Traverser$TreeTraverser