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.ClosingFuture$ClosingCallable<V>
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: com.google.common.util.concurrent.ClosingFuture$ClosingCallable
  super_class: java.lang.Object
{
  public abstract V call(com.google.common.util.concurrent.ClosingFuture$DeferredCloser);
    descriptor: (Lcom/google/common/util/concurrent/ClosingFuture$DeferredCloser;)Ljava/lang/Object;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Exceptions:
      throws java.lang.Exception
    Signature: (Lcom/google/common/util/concurrent/ClosingFuture$DeferredCloser;)TV;
    MethodParameters:
        Name  Flags
      closer  
}
Signature: <V:Ljava/lang/Object;>Ljava/lang/Object;
SourceFile: "ClosingFuture.java"
NestHost: com.google.common.util.concurrent.ClosingFuture
InnerClasses:
  public abstract ClosingCallable = com.google.common.util.concurrent.ClosingFuture$ClosingCallable of com.google.common.util.concurrent.ClosingFuture
  public final DeferredCloser = com.google.common.util.concurrent.ClosingFuture$DeferredCloser of com.google.common.util.concurrent.ClosingFuture
    RuntimeVisibleAnnotations: 
      java.lang.FunctionalInterface()
    RuntimeVisibleTypeAnnotations: 
      CLASS_TYPE_PARAMETER_BOUND
        org.checkerframework.checker.nullness.qual.Nullable()