public static PoolType valueOf(String poolTypeName, PoolType defaultPoolType) {
      PoolType poolType = PoolType.fuzzyMatch(poolTypeName);
      return (poolType != null) ? poolType : defaultPoolType;
    }
The <code>PoolMap</code> maps a key to a collection of values, the elements of which are managed
by a pool. In effect, that collection acts as a shared pool of resources, access to which is
closely controlled as per the semantics of the pool.
<p>
In case the size of the pool is set to a non-zero positive number, that is used to cap the number
of resources that a pool may contain for any given key. A size of {@link Integer#MAX_VALUE} is
interpreted as an unbounded pool.
</p>
<p>
PoolMap is thread-safe. It does not remove elements automatically. Unused resources must be
closed and removed explicitly.
</p>
@param <K> the type of the key to the resource
@param <V> the type of the resource being pooled
hbase-client/src/main/java/org/apache/hadoop/hbase/util/PoolMap.java