https://openjdk.java.net/ 
public interface javax.lang.model.type.UnionType extends javax.lang.model.type.TypeMirror
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: javax.lang.model.type.UnionType
  super_class: java.lang.Object
{
  public abstract java.util.List<? extends javax.lang.model.type.TypeMirror> getAlternatives();
    descriptor: ()Ljava/util/List;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()Ljava/util/List<+Ljavax/lang/model/type/TypeMirror;>;
}
SourceFile: "UnionType.java"