https://source.android.com/ 
public interface android.provider.Contacts$ExtensionsColumns
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: android.provider.Contacts$ExtensionsColumns
  super_class: java.lang.Object
{
  public static final java.lang.String NAME;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "name"
    RuntimeVisibleAnnotations: 
      java.lang.Deprecated()

  public static final java.lang.String VALUE;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "value"
    RuntimeVisibleAnnotations: 
      java.lang.Deprecated()
}
SourceFile: "Contacts.java"
NestHost: android.provider.Contacts
InnerClasses:
  public abstract ExtensionsColumns = android.provider.Contacts$ExtensionsColumns of android.provider.Contacts
    RuntimeVisibleAnnotations: 
      java.lang.Deprecated()