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.util.concurrent.AsyncFunction<I, O>
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: com.google.common.util.concurrent.AsyncFunction
  super_class: java.lang.Object
{
  public abstract com.google.common.util.concurrent.ListenableFuture<O> apply(I);
    descriptor: (Ljava/lang/Object;)Lcom/google/common/util/concurrent/ListenableFuture;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Exceptions:
      throws java.lang.Exception
    Signature: (TI;)Lcom/google/common/util/concurrent/ListenableFuture<TO;>;
    RuntimeVisibleTypeAnnotations: 
      METHOD_FORMAL_PARAMETER
        org.checkerframework.checker.nullness.qual.Nullable()
    MethodParameters:
       Name  Flags
      input  
}
Signature: <I:Ljava/lang/Object;O:Ljava/lang/Object;>Ljava/lang/Object;
SourceFile: "AsyncFunction.java"
    RuntimeVisibleAnnotations: 
      java.lang.FunctionalInterface()
    RuntimeInvisibleAnnotations: 
      com.google.common.annotations.GwtCompatible()