https://tomcat.apache.org/: Tomcat Servlet Engine Core Classes and Standard implementations 
public interface org.apache.catalina.realm.X509UsernameRetriever
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: org.apache.catalina.realm.X509UsernameRetriever
  super_class: java.lang.Object
{
  public abstract java.lang.String getUsername(java.security.cert.X509Certificate);
    descriptor: (Ljava/security/cert/X509Certificate;)Ljava/lang/String;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
      Name  Flags
      cert  
}
SourceFile: "X509UsernameRetriever.java"