https://developers.google.com/protocol-buffers/protobuf-java/: Core Protocol Buffers library. Protocol Buffers are a way of encoding structured data in an efficient yet extensible format. 
public interface com.google.protobuf.GeneratedMessage$BuilderParent extends com.google.protobuf.AbstractMessage$BuilderParent
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: com.google.protobuf.GeneratedMessage$BuilderParent
  super_class: java.lang.Object
{
}
SourceFile: "GeneratedMessage.java"
NestHost: com.google.protobuf.GeneratedMessage
InnerClasses:
  protected abstract BuilderParent = com.google.protobuf.AbstractMessage$BuilderParent of com.google.protobuf.AbstractMessage
  protected abstract BuilderParent = com.google.protobuf.GeneratedMessage$BuilderParent of com.google.protobuf.GeneratedMessage