public CacheSimpleConfig setMerkleTreeConfig(@Nonnull MerkleTreeConfig merkleTreeConfig) {
        this.merkleTreeConfig = checkNotNull(merkleTreeConfig, "MerkleTreeConfig cannot be null");
        return this;
    }
@Test
    public void givenNullMerkleTreeConfig_throws_NPE() {
        CacheSimpleConfig cacheSimpleConfig = new CacheSimpleConfig();
        assertThrows(NullPointerException.class, () -> cacheSimpleConfig.setMerkleTreeConfig(null));
    }