Add @nullable annotations to 2 methods of Constructor. (#75)

Author: cpovirk

src/java.base/share/classes/java/lang/reflect/Constructor.java

@@ -590,7 +590,7 @@ byte[] getRawParameterAnnotations() {
      * @throws NullPointerException  {@inheritDoc}
      * @since 1.5
      */
-    public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
+    public <T extends Annotation> @Nullable T getAnnotation(Class<T> annotationClass) {
         return super.getAnnotation(annotationClass);
     }
 
@@ -644,7 +644,7 @@ public AnnotatedType getAnnotatedReturnType() {
      * @since 1.8
      */
     @Override
-    public AnnotatedType getAnnotatedReceiverType() {
+    public @Nullable AnnotatedType getAnnotatedReceiverType() {
         Class<?> thisDeclClass = getDeclaringClass();
         Class<?> enclosingClass = thisDeclClass.getEnclosingClass();