public synchronized void acquire() {
      users.incrementAndGet();
      if (users.get() > 1) {
        LOG.warn("Unexpected increment of user count beyond one: " + users.get() + " " + this);
      }
    }
Increments the user count and optionally renews the expiration time.
<code>renew</code> should correspond with the expiration policy of the cache.
When the policy is <code>expireAfterAccess</code>, the expiration time should be extended.
When the policy is <code>expireAfterWrite</code>, the expiration time should not be extended.
A mismatch with the policy will lead to closing the connection unnecessarily after the initial
expiration time is generated.
@param renew whether the expiration time should be extended.
hcatalog/core/src/main/java/org/apache/hive/hcatalog/common/HiveClientCache.java