@Override
        public void close() {
            if (!closed) {
                if (available) {
                    LOGGER_CONNECTION.debug("Releasing connection");
                    lock.release();
                    available = false;
                }

                closed = true;
                onClose();
                counter.decrementAndGet();
            }
        }
Configuration parameter that controls if a request for a new connection
should be queued until one becomes available or if it should cause an
exception to be thrown if no connection is available.
runtime-parent/runtime-core/src/main/java/com/speedment/runtime/core/component/connectionpool/SingletonConnectionPoolComponent.java