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 interface com.google.common.graph.SuccessorsFunction<N>
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: com.google.common.graph.SuccessorsFunction
  super_class: java.lang.Object
{
  public abstract java.lang.Iterable<? extends N> successors(N);
    descriptor: (Ljava/lang/Object;)Ljava/lang/Iterable;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: (TN;)Ljava/lang/Iterable<+TN;>;
    MethodParameters:
      Name  Flags
      node  
}
Signature: <N:Ljava/lang/Object;>Ljava/lang/Object;
SourceFile: "SuccessorsFunction.java"
    RuntimeVisibleAnnotations: 
      com.google.errorprone.annotations.DoNotMock(value = "Implement with a lambda, or use GraphBuilder to build a Graph with the desired edges")
    RuntimeInvisibleAnnotations: 
      com.google.common.annotations.Beta()