Add Name.isEmpty

Summary

Provide an method explicitly corresponding to the "empty name" concept mentioned repeated in the javax.lang.model API.

Problem

The javax.lang.model API repeatedly uses the concept of an "empty name." With the CharSequence superinterface of Name having an isEmpty default method as of 15, it is helpful to have an innocuous override fo isEmpty is Name to ease references to the empty name concept from other parts of the API.

Solution

Add an innocuous override of CharSequence::isEmpty to javax.lang.model.Name.

Specification

 public interface Name extends CharSequence {
     /**
+     * Returns {@code true} if this is an empty name with a length of
+     * zero; returns {@code false} otherwise.
+     * @return {@code true} for an empty name and {@code false} otherwise.
+     *
+     * @implSpec Returns the result of calling {@link
+     * CharSequence#isEmpty() CharSequence.isEmpty()}.
+     * @since 16
+     */
+    @Override
+    default boolean isEmpty() {
+        return CharSequence.super.isEmpty();
+    }