int getPooledBufferCount(final int minCapacity) {
        final int offset = getOffset(minCapacity);
        return pooledBufferCounters[offset].get();
    }
For testing.

@return Number of buffers known to the pool, i.e. in the pool or on loan.
stroom-bytebuffer/src/main/java/stroom/bytebuffer/ByteBufferPoolImpl4.java