Knows how to get the value of a specified annotation element on a
 target class. 
 User code:
 
 @MyAnnotation(intValue = 1, stringValue = "", classValue = System.class)
 class MyClass
 {
 }
 @interface MyAnnotation
 {
   int intValue();
   String stringValue();
   Class classValue();
 }
 
 DT code:
 
   // myAnnotation is the JavaType representing the class MyAnnotation.
   // myClass is the JavaType representing the class MyClass.
   final JavaType myAnnotation;
   final JavaType myClass;
   final AnnotationValueGetter<Integer> intGetter =
     Annotations.integerGetter(myAnnotation, "intValue");
   final Integer one = intGetter.get(myClass);
   final AnnotationValueGetter<String> stringGetter =
     Annotations.stringGetter(myAnnotation, "stringValue");
   final String empty = stringGetter.get(myClass);
   final AnnotationValueGetter<Class> classGetter =
     Annotations.classGetter(myAnnotation, "classValue");
   final Class systemClass = classGetter.get(myClass);