@SubtypeOf(value=SignatureUnknown.class) @Target(value={TYPE_USE,TYPE_PARAMETER}) public @interface FieldDescriptor
For example, in
  package org.checkerframework.checker.signature;
  public class SignatureChecker {
    private class Inner {}
  }
 
 the field descriptors for the two types are
 Lorg/checkerframework/checker/signature/SignatureChecker; and
 Lorg/checkerframework/checker/signature/SignatureChecker$Inner; .