boolean reserveForBecomePrimary() {
      synchronized (BucketAdvisor.this) {
        if (volunteeringThread != null) {
          return false;
        }
        aggressive = true;
        return true;
      }
    }
Reserves this delegate for the current thread to call becomePrimary. Necessary because caller
of doVolunteerForPrimary must not be synchronized on BucketAdvisor.

@return true if successfully reserved for becomePrimary
geode-core/src/main/java/org/apache/geode/internal/cache/BucketAdvisor.java