public QueryCacheConfig setBufferSize(int bufferSize) {
        this.bufferSize = checkPositive("bufferSize", bufferSize);
        return this;
    }
@Test(expected = IllegalArgumentException.class)
    public void testSetBufferSize_throwsException_whenNotPositive() {
        QueryCacheConfig config = new QueryCacheConfig();
        config.setBufferSize(-1);
    }