https://lucene.apache.org/lucene-parent/lucene-core: Apache Lucene Java Core (The Apache Software Foundation) 
public interface org.apache.lucene.index.IndexSorter$DocComparator
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: org.apache.lucene.index.IndexSorter$DocComparator
  super_class: java.lang.Object
{
  public abstract int compare(int, int);
    descriptor: (II)I
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
        Name  Flags
      docID1  
      docID2  
}
SourceFile: "IndexSorter.java"
NestHost: org.apache.lucene.index.IndexSorter
InnerClasses:
  public abstract DocComparator = org.apache.lucene.index.IndexSorter$DocComparator of org.apache.lucene.index.IndexSorter