private void checkDestroyed() {
      if (destroyed) {
        String s = "Attempting to use destroyed grant token: " + this;
        throw new IllegalStateException(s);
      }
    }
Throws IllegalStateException if this grant token has been destroyed.
<p>
Caller must synchronize on this grant token.

@throws IllegalStateException if this grant token has been destroyed guarded.By this
geode-core/src/main/java/org/apache/geode/distributed/internal/locks/DLockGrantor.java