public interface io.reactivex.internal.fuseable.HasUpstreamSingleSource<T>
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: io.reactivex.internal.fuseable.HasUpstreamSingleSource
  super_class: java.lang.Object
{
  public abstract io.reactivex.SingleSource<T> source();
    descriptor: ()Lio/reactivex/SingleSource;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()Lio/reactivex/SingleSource<TT;>;
}
Signature: <T:Ljava/lang/Object;>Ljava/lang/Object;
SourceFile: "HasUpstreamSingleSource.java"